InformationThe /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.
Since the /var directory may contain world-writable files and directories, there is a risk of resource exhaustion if it is not bound to a separate partition.
SolutionFor new installations, during installation create a custom partition setup and specify a separate partition for /var .
For systems that were previously installed, create a new partition and configure /etc/fstab as appropriate.
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.
AJ Lewis, 'LVM HOWTO', http://tldp.org/HOWTO/LVM-HOWTO/
When modifying /var 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 multiuser mode.
This Benchmark recommendation maps to:
Red Hat Enterprise Linux 7 Security Technical Implementation Guide:
Version 2, Release: 3 Benchmark Date: 26 Apr 2019
Vul ID: V-72061
Rule ID: SV-86685r2_rule
STIG ID: RHEL-07-021320
Severity: CAT III