Vulnerability Discussion

The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files as they may be incompatible. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.

The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.

The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.

Check

Verify that the "nodev","nosuid", and "noexec" options are configured for /dev/shm:

# cat /etc/fstab | grep /dev/shm

tmpfs /dev/shm tmpfs defaults,nodev,nosuid,noexec 0 0

If results are returned and the "nodev", "nosuid", or "noexec" options are missing, this is a finding.

Verify "/dev/shm" is mounted with the "nodev", "nosuid", and "noexec" options:

# mount | grep /dev/shm

tmpfs on /dev/shm type tmpfs (rw,nodev,nosuid,noexec,seclabel)

If /dev/shm is mounted without secure options "nodev", "nosuid", and "noexec", this is a finding.

Fix

Configure the system so that /dev/shm is mounted with the "nodev", "nosuid", and "noexec" options by adding /modifying the /etc/fstab with the following line:

tmpfs /dev/shm tmpfs defaults,nodev,nosuid,noexec 0 0