cyberstrikeus Ensure mounting of cramfs filesystems is disabled
Description
The cramfs filesystem type is a compressed read-only Linux filesystem embedded in small footprint systems. A cramfs image can be used without having to first decompress the image.
Rationale
Removing support for unneeded filesystem types reduces the local attack surface of the server. If this filesystem type is not needed, disable it.
Impact
None noted.
Audit Procedure
Command Line
# modprobe -n -v cramfs | grep -E '(cramfs|install)'
# lsmod | grep cramfs
Expected Result
install /bin/true
The lsmod command should return no output.
Remediation
Command Line
# Edit or create a file in the /etc/modprobe.d/ directory ending in .conf
# Example: vim /etc/modprobe.d/cramfs.conf
# and add the following line:
install cramfs /bin/true
# Run the following command to unload the cramfs module:
rmmod cramfs
Default Value
Not disabled by default.
References
- CIS Controls Version 7 - 5.1 Establish Secure Configurations: Maintain documented, standard security configuration standards for all authorized operating systems and software.
Profile
Level 1 - Server / Level 1 - Workstation, Assessment: Automated