cyberstrikeus Ensure separate partition exists for /home
Profile
Level 2 - Server, Level 2 - Workstation, Assessment: Automated
Description
The /home directory is used to support disk storage needs of local users.
Rationale
The default installation only creates a single / partition. Since the /home directory contains user generated data, there is a risk of resource exhaustion. It will essentially have the whole disk available to fill up and impact the system as a whole. In addition, other operations on the system could fill up the disk unrelated to /home and impact all local users.
Configuring /home as its own file system allows an administrator to set additional mount options such as noexec/nosuid/nodev. These options limit an attacker's ability to create exploits on the system. In the case of /home options such as usrquota/grpquota may be considered to limit the impact that users can have on each other with regards to disk resource exhaustion. Other options allow for specific behavior. See man mount for exact details regarding filesystem-independent and filesystem-specific options.
As /home contains user data, care should be taken to ensure the security and integrity of the data and mount point.
Impact
Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem partitions may prevent successful resizing or may require the installation of additional tools solely for the purpose of resizing operations. The use of these additional tools may introduce their own security considerations.
Audit Procedure
Command Line
Run the following command and verify output shows /home is mounted.
# findmnt -kn /home
Example output:
/home /dev/sdb ext4 rw,nosuid,nodev,relatime,seclabel
Expected Result
/home should be mounted as a separate partition.
Remediation
Command Line
For new installations, during installation create a custom partition setup and specify a separate partition for /home.
For systems that were previously installed, create a new partition and configure /etc/fstab as appropriate.
Default Value
Not configured by default.
Additional Information
When modifying /home it is advisable to bring the system to emergency mode (so auditd is not running), rename the existing directory, mount the new file system, and migrate the data over before returning to multi-user mode.
References
- AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
- NIST SP 800-53 Rev. 5: CM-7
CIS Controls
v8 - 3.3 Configure Data Access Control Lists (IG 1, IG 2, IG 3) v7 - 14.6 Protect Information through Access Control Lists (IG 1, IG 2, IG 3)
MITRE ATT&CK Mappings: T1499, T1499.001 | TA0005 | M1038