cyberstrikeus Ensure separate partition exists for /var
Profile
Level 2 - Server / Level 2 - Workstation, Assessment: Automated
Description
The /var directory is used by daemons and other system services to temporarily store dynamic data. Some directories created by these processes may be world-writable.
Rationale
The reasoning for mounting /var on a separate partition is to provide protection in case of a software or configuration error that causes excessive disk consumption in /var. Since /var contains the bulk of dynamic system data such as logs, mail spools, and package manager cache, isolating it prevents a runaway process from filling the root filesystem.
Impact
Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem partitions may prevent tying the overall disk management to one large volume. It may be necessary to use Logical Volume Management (LVM) or similar tools to create a flexible partitioning scheme for /var.
Audit Procedure
Command Line
Run the following command and verify the output shows that /var is mounted:
# findmnt -kn /var
Expected Result
/var /dev/sda2 ext4 rw,relatime,seclabel
Remediation
Command Line
For specific configuration requirements of the /var mount for your environment, modify /etc/fstab:
# Configure /etc/fstab as appropriate:
# Example:
# <device> /var <fstype> defaults,rw,nosuid,nodev,relatime 0 0
Creating a new partition is a destructive operation that typically requires a reinstallation or use of LVM.
Default Value
By default /var is not a separate partition.
References
- http://tldp.org/HOWTO/LVM-HOWTO/
- NIST SP 800-53 Rev. 4: MP-2, AC-3
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 (TA0006) - M1022