1.1.15 Ensure nodev option set on /dev/shm partition (Scored)
Profile Applicability
Level 1 - Server Level 1 - Workstation
Description
The nodev
mount option specifies that the filesystem cannot contain special devices.
Rationale
Since the /dev/shm
filesystem is not intended to support devices, set this option to ensure that users cannot attempt to create special devices in /dev/shm
partitions.
Audit
Run the following command and verify that the nodev
option is set on /dev/shm
.
# mount | grep /dev/shm tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime)
Remediation
Edit the /etc/fstab
file and add nodev
to the fourth field (mounting options) for the /dev/shm
partition. See the fstab(5)
manual page for more information.
Run the following command to remount /dev/shm
:
# mount -o remount,nodev /dev/shm
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.
Notes
/dev/shm
is not specified in /etc/fstab
despite being mounted by default. The following line will implement the recommended /dev/shm
mount options in /etc/fstab
:
tmpfs /dev/shm tmpfs defaults,nodev,nosuid,noexec 0 0