1.1.7 Ensure separate partition exists for /var/tmp


The /var/tmp directory is a world-writable directory used for temporary storage by all
users and some applications.


Since the /var/tmp directory is intended to be world-writable, there is a risk of resource
exhaustion if it is not bound to a separate partition. In addition, making /var/tmp its own
file system allows an administrator to set the noexec option on the mount, making
/var/tmp useless for an attacker to install executable code. It would also prevent an
attacker from establishing a hardlink to a system setuid program and wait for it to be
updated. Once the program was updated, the hardlink would be broken and the attacker
would have his own copy of the program. If the program happened to have a security
vulnerability, the attacker could continue to exploit the known flaw.


For new installations, during installation create a custom partition setup and specify a
separate partition for /var/tmp .
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.,CSCv6|13,CSCv7|5.1

See Also