/thm-furthernmap

Further Nmap - Try Hack Me (https://tryhackme.com/)

Further Nmap

Crenata | Thursday, October 28th, 2021

Link : https://tryhackme.com/room/furthernmap

Introduction

  • What networking constructs are used to direct traffic to the right application on a server?
Ports
  • How many of these are available on any network-enabled computer?
65535
  • [Research] How many of these are considered "well-known"? (These are the "standard" numbers mentioned in the task)
1024

Nmap Switches

  • What is the first switch listed in the help menu for a 'Syn Scan' (more on this later!)?
-sS
  • Which switch would you use for a "UDP scan"?
-sU
  • If you wanted to detect which operating system the target is running on, which switch would you use?
-O
  • Nmap provides a switch to detect the version of the services running on the target. What is this switch?
-sV
  • The default output provided by nmap often does not provide enough information for a pentester. How would you increase the verbosity?
-v
  • Verbosity level one is good, but verbosity level two is better! How would you set the verbosity level to two? (Note: it's highly advisable to always use at least this option)
-vv
  • We should always save the output of our scans -- this means that we only need to run the scan once (reducing network traffic and thus chance of detection), and gives us a reference to use when writing reports for clients. What switch would you use to save the nmap results in three major formats?
-oA
  • What switch would you use to save the nmap results in a "normal" format?
-oN
  • A very useful output format: how would you save results in a "grepable" format?
-oG
  • Sometimes the results we're getting just aren't enough. If we don't care about how loud we are, we can enable "aggressive" mode. This is a shorthand switch that activates service detection, operating system detection, a traceroute and common script scanning. How would you activate this setting?
-A
  • Nmap offers five levels of "timing" template. These are essentially used to increase the speed your scan runs at. Be careful though: higher speeds are noisier, and can incur errors! How would you set the timing template to level 5?
-T5
  • We can also choose which port(s) to scan. How would you tell nmap to only scan port 80?
-p 80
  • How would you tell nmap to scan ports 1000-1500?
-p 1000-1500
  • A very useful option that should not be ignored: How would you tell nmap to scan all ports?
-p-
  • How would you activate a script from the nmap scripting library (lots more on this later!)?
--script
  • How would you activate all of the scripts in the "vuln" category?
--script=vuln

Scan Types TCP Connect Scans

  • Which RFC defines the appropriate behaviour for the TCP protocol?
RFC 793
  • If a port is closed, which flag should the server send back to indicate this?
RST

Scan Types SYN Scans

  • There are two other names for a SYN scan, what are they?
Half-Open, Stealth
  • Can Nmap use a SYN scan without Sudo permissions (Y/N)?
N

Scan Types UDP Scans

  • If a UDP port doesn't respond to an Nmap scan, what will it be marked as?
open|filtered
  • When a UDP port is closed, by convention the target should send back a "port unreachable" message. Which protocol would it use to do so?
ICMP

Scan Types NULL, FIN and Xmas

  • Which of the three shown scan types uses the URG flag?
xmas
  • Why are NULL, FIN and Xmas scans generally used?
Firewall Evasion
  • Which common OS may respond to a NULL, FIN or Xmas scan with a RST for every port?
Microsoft Windows

Scan Types ICMP Network Scanning

  • How would you perform a ping sweep on the 172.16.x.x network (Netmask: 255.255.0.0) using Nmap? (CIDR notation)
nmap -sn 172.16.0.0/16

NSE Scripts Overview

  • What language are NSE scripts written in?
Lua
  • Which category of scripts would be a very bad idea to run in a production environment?
Intrusive

NSE Scripts Working with the NSE

  • What optional argument can the ftp-anon.nse script take?
maxlist

NSE Scripts Searching for Scripts

  • Search for "smb" scripts in the /usr/share/nmap/scripts/ directory using either of the demonstrated methods. What is the filename of the script which determines the underlying OS of the SMB server?
smb-os-discovery.nse
  • Read through this script. What does it depend on?
smb-brute

Firewall Evasion

  • Which simple (and frequently relied upon) protocol is often blocked, requiring the use of the -Pn switch?
ICMP
  • [Research] Which Nmap switch allows you to append an arbitrary length of random data to the end of packets?
--data-length

Practical

  • Does the target (MACHINE_IP)respond to ICMP (ping) requests (Y/N)?
N
  • Perform an Xmas scan on the first 999 ports of the target -- how many ports are shown to be open or filtered?
999
  • There is a reason given for this -- what is it? Note: The answer will be in your scan results. Think carefully about which switches to use -- and read the hint before asking for help!
No Response
  • Perform a TCP SYN scan on the first 5000 ports of the target -- how many ports are shown to be open?
5
  • Deploy the ftp-anon script against the box. Can Nmap login successfully to the FTP server on port 21? (Y/N)
Y