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.

Firejail Intro	Firejail Demo	Debian Install
Arch Linux Install	Disable Network Access	Firejail Security Deep Dive

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.youtube.com/channel/UCi5u-syndQYyOeV4NZ04hNA

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 [email protected]

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/

Try installing Firejail from your system packages first. 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.

The firejail 0.9.52-LTS version is deprecated. On Ubuntu 18.04 LTS users are advised to use the PPA. On Debian buster we recommend to use the backports package.

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:https:///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 /usr/lib/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:

• https://github.com/chiraag-nataraj/firejail-profiles

• https://github.com/triceratops1/fe

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: #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: #4379

We are adding IDS capabilities in the next release. We have the list of files in /etc/firejail/ids.config, and we generate a BLAKE2 checksum in /var/lib/firejail/username.ids. The program runs as regular user, each user has his own file in /var/lib/firejail.

Initialize the database:

$ firejail --ids-init
Loading /etc/firejail/ids.config config file
500 1000 1500 2000
2457 files scanned
IDS database initialized

Later, we check it:

$ firejail --ids-check
Loading /etc/firejail/ids.config config file
500 1000 1500
Warning: modified /home/netblue/.bashrc
2000
2457 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 followed, 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).

A small tool to print profile statistics. Compile as usual and run in /etc/profiles:

$ sudo cp src/profstats/profstats /etc/firejail/.
$ cd /etc/firejail
$ ./profstats *.profile
    profiles			1150
    include local profile	1150   (include profile-name.local)
    include globals		1120   (include globals.local)
    blacklist ~/.ssh		1026   (include disable-common.inc)
    seccomp			1050
    capabilities		1146
    noexec			1030   (include disable-exec.inc)
    noroot			959
    memory-deny-write-execute	253
    apparmor			681
    private-bin			667
    private-dev			1009
    private-etc			523
    private-tmp			883
    whitelist home directory	547
    whitelist var		818   (include whitelist-var-common.inc)
    whitelist run/user		616   (include whitelist-runuser-common.inc
					or blacklist ${RUNUSER})
    whitelist usr/share		591   (include whitelist-usr-share-common.inc
    net none			391
    dbus-user none 		641
    dbus-user filter 		105
    dbus-system none 		792
    dbus-system filter 		7

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