Stable Features[edit]

Described here ^[archive].

Testing Features[edit]

Reduce Kernel Information Leaks[edit]

• Security Impact: There are many of hardware, kernel, debug information, etc. in /sys, which is especially problematic and has been the cause of many infoleaks such as kernel pointer leaks.
• Privacy/Anonymity Impact: Details about your hardware can be used for identification.
• Threat: This information is per Debian (and probably most popular Linux distributions) available to attackers with local code execution privileges which includes,
  • malicious applications collecting such information and submitting it to data collectors,
  • as well as both, compromised non-privileged users and the privileged root user.
• Non-Threat: This information does not randomly leak to third parties on clean (non-compromised) machines through use of legitimate applications such as the APT package manager.
• Goal: This information should by default be unavailable to non-privileged users and untrusted root.
• Solution: Therefore security-misc includes the hide-hardware-info.service systemd unit.
  • Restricts access to /sys, /proc/cpuinfo, /proc/bus, and /proc/scsi to the root user only.
  • This also hides most hardware identifiers.
• Status: This setting is disabled by default because it might break many applications. Testers-only! Call for testers and forum discussion: Restrict Hardware Information to Root - Testers Wanted! ^[archive]
• Enable: It can optionally be enabled by running the following command.

  • sudo systemctl enable hide-hardware-info.service

    sudo systemctl enable hide-hardware-info.service

  • Reboot required.
  • A whitelist that allows specific applications to access /sys and /proc/cpuinfo is enabled by default to maintain basic functionality. ^[1] For example, this allows the launching of applications like XFCE.
• Limitations of Solution:
  • Attackers which gained root compromise and/or malicious/compromised whitelisted applications have access to this information.
  • Cannot hide CPUID ^[archive]. ^[2]
• Possible Future Enhancements: untrusted root

Whitelisting Applications[edit]

To whitelist applications, they must be run under the sysfs group (if allowing access to /sys) and/or the cpuinfo group (if allowing access to /proc/cpuinfo).

Remember that any whitelisted applications add to the attack surface. An attacker can attempt to exploit a vulnerability in the whitelisted application(s) to gain access to hardware information.

addgroup method[edit]

For example, to add user user to group cpuinfo, run the following command. (Note, this is weakening protections.)

sudo addgroup user cpuinfo

For example, to add user user to group sysfs, run the following command. (Note, this is weakening protections.)

sudo addgroup user sysfs

Re-login required after changing groups. Easiest: reboot. ^{[3] [4]}

For example, after reboot it would be possible to run the cpu-info utility (from Debian package cpuinfo).

cpu-info

systemd[edit]

For example, to run a systemd service as the sysfs group, create a drop-in directory and add the following.

[Service]
SupplementaryGroups=sysfs

setgid method[edit]

To run a specific binary as the sysfs group, the binary must be owned by the sysfs group and be made setgid. To achieve this, change the ownership of the binary by running the following.

sudo chgrp sysfs /path/to/binary

Then make the binary setgid.

sudo chmod g+s /path/to/binary

The binary will now run with the permissions of the sysfs group and have access to /sys.

All of these steps can also be applied to the cpuinfo group.

Disable the Whitelist[edit]

In order to reduce the attack surface as much as possible, optionally the whitelist can be disabled entirely.

1. Open file /etc/hide-hardware-info.d/50_user.conf in an editor with root rights.

sudoedit /etc/hide-hardware-info.d/50_user.conf

2. Add.

sysfs_whitelist=0
cpuinfo_whitelist=0

3. Save.

4. Done.

SUID Disabler and Permission Hardener[edit]

See SUID Disabler and Permission Hardener.

hidepid[edit]

TODO: document

sudo systemctl enable proc-hidepid.service

Experimental Features[edit]

Unreleased. (Developers only.) Will flow into other repositories as per usual.

Remount Secure[edit]

Feature not ready!

• https://forums.whonix.org/t/re-mount-home-and-other-with-noexec-and-nosuid-among-other-useful-mount-options-for-better-security/7707/27 ^[archive]
• https://github.com/Whonix/security-misc/blob/master/lib/systemd/system/remount-secure.service ^[archive]
• https://github.com/Whonix/security-misc/blob/master/usr/lib/security-misc/remount-secure ^[archive]
• Dev/remount-secure

sudo touch /etc/noexec

Installation of security-misc[edit]

Prerequisites:

su -

apt update

apt full-upgrade

apt install --no-install-recommends sudo adduser

addgroup --system console

adduser user console

adduser user sudo

reboot

wget https://www.whonix.org/derivative.asc

sudo cp derivative.asc /usr/share/keyrings/derivative.asc

echo "deb [signed-by=/usr/share/keyrings/derivative.asc] https://deb.whonix.org bullseye main contrib non-free" | sudo tee /etc/apt/sources.list.d/derivative.list

sudo apt update

sudo apt full-upgrade

sudo apt install --no-install-recommends security-misc

selinux[edit]

Community Support Only!:
	Community Support Only means Whonix ™ developers are unlikely to provide free support for wiki chapters or pages with this tag. See Community Support for further information, including implications and possible alternatives.

• https://github.com/Whonix/security-misc/pull/100 ^[archive]
• https://forums.whonix.org/t/restrict-hardware-information-to-root/7329/88 ^[archive]

References[edit]

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