Firejail is a SUID sandbox program that reduces the risk of security breaches by restricting the running environment of untrusted applications using Linux namespaces, seccomp-bpf and Linux capabilities. It allows a process and all its descendants to have their own private view of the globally shared kernel resources, such as the network stack, process table, mount table. Firejail can work in a SELinux or AppArmor environment, and it is integrated with Linux Control Groups.
Written in C with virtually no dependencies, the software runs on any Linux computer with a 3.x kernel version or newer. It can sandbox any type of processes: servers, graphical applications, and even user login sessions. The software includes sandbox profiles for a number of more common Linux programs, such as Mozilla Firefox, Chromium, VLC, Transmission etc.
The sandbox is lightweight, the overhead is low. There are no complicated configuration files to edit, no socket connections open, no daemons running in the background. All security features are implemented directly in Linux kernel and available on any Linux computer.
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Project webpage: https://firejail.wordpress.com/
Download and Installation: https://firejail.wordpress.com/download-2/
Features: https://firejail.wordpress.com/features-3/
Documentation: https://firejail.wordpress.com/documentation-2/
FAQ: https://github.com/netblue30/firejail/wiki/Frequently-Asked-Questions
Wiki: https://github.com/netblue30/firejail/wiki
GitLab-CI status: https://gitlab.com/Firejail/firejail_ci/pipelines/
Video Channel: https://www.brighteon.com/channels/netblue30
Backup Video Channel: https://www.bitchute.com/profile/JSBsA1aoQVfW/
We take security bugs very seriously. If you believe you have found one, please report it by emailing us at netblue30@protonmail.com
Security Advisory - Feb 8, 2021
Summary: A vulnerability resulting in root privilege escalation was discovered in
Firejail's OverlayFS code,
Versions affected: Firejail software versions starting with 0.9.30.
Long Term Support (LTS) Firejail branch is not affected by this bug.
Workaround: Disable overlayfs feature at runtime.
In a text editor open /etc/firejail/firejail.config file, and set "overlayfs" entry to "no".
$ grep overlayfs /etc/firejail/firejail.config
# Enable or disable overlayfs features, default enabled.
overlayfs no
Fix: The bug is fixed in Firejail version 0.9.64.4
GitHub commit: (file configure.ac)
https://github.com/netblue30/firejail/commit/97d8a03cad19501f017587cc4e47d8418273834b
Credit: Security researcher Roman Fiedler analyzed the code and discovered the vulnerability.
Functional PoC exploit code was provided to Firejail development team.
A description of the problem is here on Roman's blog:
https://unparalleled.eu/publications/2021/advisory-unpar-2021-0.txt
https://unparalleled.eu/blog/2021/20210208-rigged-race-against-firejail-for-local-root/
Debian stable (bullseye): We recommend to use the backports package.
For Ubuntu 18.04+ and derivatives (such as Linux Mint), users are strongly advised to use the PPA.
How to add and install from the PPA:
sudo add-apt-repository ppa:deki/firejail
sudo apt-get update
sudo apt-get install firejail firejail-profilesReason: The firejail package for Ubuntu 20.04 has been left vulnerable to CVE-2021-26910 for months after a patch for it was posted on Launchpad:
See also https://wiki.ubuntu.com/SecurityTeam/FAQ:
What software is supported by the Ubuntu Security team?
Ubuntu is currently divided into four components: main, restricted, universe and multiverse. All binary packages in main and restricted are supported by the Ubuntu Security team for the life of an Ubuntu release, while binary packages in universe and multiverse are supported by the Ubuntu community.
Additionally, the PPA version is likely to be more recent and to contain more profile fixes.
See the following discussions for details:
- Should I keep using the version of firejail available in my distro repos?
- How to install the latest version on Ubuntu and derivatives
Try installing Firejail from your distribution.
Firejail is included in Alpine, ALT Linux, Arch, Artix, Chakra, Debian, Deepin, Devuan, Fedora, Gentoo, Manjaro, Mint, NixOS, Parabola, Parrot, PCLinuxOS, ROSA, Solus, Slackware/SlackBuilds, Trisquel, Ubuntu, Void and possibly others.
Note: The firejail 0.9.52-LTS version is deprecated.
You can also install one of the released packages, or clone Firejail’s source code from our Git repository and compile manually:
$ git clone https://github.com/netblue30/firejail.git
$ cd firejail
$ ./configure && make && sudo make install-strip
On Debian/Ubuntu you will need to install git and gcc compiler. AppArmor
development libraries and pkg-config are required when using --apparmor
./configure option:
$ sudo apt-get install git build-essential libapparmor-dev pkg-config gawk
For --selinux option, add libselinux1-dev (libselinux-devel for Fedora).
Detailed information on using firejail from git is available on the wiki.
To start the sandbox, prefix your command with firejail:
$ firejail firefox # starting Mozilla Firefox
$ firejail transmission-gtk # starting Transmission BitTorrent
$ firejail vlc # starting VideoLAN Client
$ sudo firejail /etc/init.d/nginx start
Run firejail --list in a terminal to list all active sandboxes. Example:
$ firejail --list
1617:netblue:/usr/bin/firejail /usr/bin/firefox-esr
7719:netblue:/usr/bin/firejail /usr/bin/transmission-qt
7779:netblue:/usr/bin/firejail /usr/bin/galculator
7874:netblue:/usr/bin/firejail /usr/bin/vlc --started-from-file file:///home/netblue/firejail-whitelist.mp4
7916:netblue:firejail --list
Integrate your sandbox into your desktop by running the following two commands:
$ firecfg --fix-sound
$ sudo firecfg
The first command solves some shared memory/PID namespace bugs in PulseAudio software prior to version 9. The second command integrates Firejail into your desktop. You would need to logout and login back to apply PulseAudio changes.
Start your programs the way you are used to: desktop manager menus, file manager, desktop launchers. The integration applies to any program supported by default by Firejail. There are about 250 default applications in current Firejail version, and the number goes up with every new release. We keep the application list in /etc/firejail/firecfg.config file.
Most Firejail command line options can be passed to the sandbox using profile files. You can find the profiles for all supported applications in /etc/firejail directory.
If you keep additional Firejail security profiles in a public repository, please give us a link:
Use this issue to request new profiles: #1139
You can also use this tool to get a list of syscalls needed by a program: contrib/syscalls.sh.
We also keep a list of profile fixes for previous released versions in etc-fixes directory.
Milestone page: https://github.com/netblue30/firejail/milestone/1 Release discussion: netblue30#3696
Moving from whitelist/blacklist to allow/deny is under way! We are still open to other options, so it might change!
The old whitelist/blacklist will remain as aliasses for the next one or two releases in order to give users a chance to switch their local profiles. The latest discussion on this issue is here: netblue30#4379
--ids-check
Check file hashes previously generated by --ids-check. See IN‐
TRUSION DETECTION SYSTEM section for more details.
Example:
$ firejail --ids-check
--ids-init
Initialize file hashes. See INTRUSION DETECTION SYSTEM section
for more details.
Example:
$ firejail --ids-init
INTRUSION DETECTION SYSTEM (IDS)
The host-based intrusion detection system tracks down and audits user
and system file modifications. The feature is configured using
/etc/firejail/ids.config file, the checksums are stored in
/var/lib/firejail/USERNAME.ids, where USERNAME is the name of the cur‐
rent user. We use BLAKE2 cryptographic function for hashing.
As a regular user, initialize the database:
$ firejail --ids-init
Opening config file /etc/firejail/ids.config
Loading config file /etc/firejail/ids.config
Opening config file /etc/firejail/ids.config.local
500 1000 1500 2000
2466 files scanned
IDS database initialized
The default configuration targets several system executables in direc‐
tories such as /bin, /sbin, /usr/bin, /usr/sbin, and several critical
config files in user home directory such as ~/.bashrc, ~/.xinitrc, and
~/.config/autostart. Several system config files in /etc directory are
also hashed.
Run --ids-check to audit the system:
$ firejail --ids-check
Opening config file /etc/firejail/ids.config
Loading config file /etc/firejail/ids.config
Opening config file /etc/firejail/ids.config.local
500 1000 1500
Warning: modified /home/netblue/.bashrc
2000
2466 files scanned: modified 1, permissions 0, new 0, removed 0
The program will print the files that have been modified since the
database was created, or the files with different access permissions.
New files and deleted files are also flagged.
Currently while scanning the file system symbolic links are not fol‐
lowed, and files the user doesn't have read access to are silently
dropped. The program can also be run as root (sudo firejail --ids-
init/--ids-check).
--deterministic-exit-code
Always exit firejail with the first child's exit status. The de‐
fault behavior is to use the exit status of the final child to
exit, which can be nondeterministic.
--deterministic-shutdown
Always shut down the sandbox after the first child has termi‐
nated. The default behavior is to keep the sandbox alive as long
as it contains running processes.
--nettrace=name|pid
Monitor TCP and UDP traffic coming into the sandbox specified by
name or pid. Only networked sandboxes created with --net are
supported.
$ firejail --nettrace=browser
9.9.9.9:53 => 192.168.1.60 UDP: 122 B/sec
72.21.91.29:80 => 192.168.1.60 TCP: 257 B/sec
80.92.126.65:123 => 192.168.1.60 UDP: 25 B/sec
69.30.241.50:443 => 192.168.1.60 TCP: 88 KB/sec
140.82.112.4:443 => 192.168.1.60 TCP: 1861 B/sec
(14 streams in the last one minute)
A small tool to print profile statistics. Compile and install as usual. The tool is installed in /usr/lib/firejail directory. Run it over the profiles in /etc/profiles:
$ /usr/lib/firejail/profstats /etc/firejail/*.profile
No include .local found in /etc/firejail/noprofile.profile
Warning: multiple caps in /etc/firejail/transmission-daemon.profile
Stats:
profiles 1176
include local profile 1175 (include profile-name.local)
include globals 1144 (include globals.local)
blacklist ~/.ssh 1050 (include disable-common.inc)
seccomp 1070
capabilities 1171
noexec 1057 (include disable-exec.inc)
noroot 979
memory-deny-write-execute 258
apparmor 700
private-bin 681
private-dev 1033
private-etc 533
private-tmp 905
whitelist home directory 562
whitelist var 842 (include whitelist-var-common.inc)
whitelist run/user 1145 (include whitelist-runuser-common.inc
or blacklist ${RUNUSER})
whitelist usr/share 614 (include whitelist-usr-share-common.inc
net none 399
dbus-user none 662
dbus-user filter 113
dbus-system none 816
dbus-system filter 10
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