cis-ubuntu1204-v110-2-1

name	cis-ubuntu1204-v110-2-1
description	Create Separate Partition for /tmp
category	cis-os-hardening
version	1.1.0
author	cyberstrike-official
tags	["cis","ubuntu",12.04,"linux","filesystem","partitioning","tmp"]
cis_id	2.1
cis_benchmark	CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

2.1 Create Separate Partition for /tmp (Scored)

Profile Applicability

• Level 1

Description

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

Rationale

Since the /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 /tmp its own file system allows an administrator to set the noexec option on the mount, making /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.

Audit Procedure

Using Command Line

grep "[[:space:]]/tmp[[:space:]]" /etc/fstab

Expected Result

A partition entry for /tmp should be returned. If the command emits no output then the system is not configured as recommended.

Remediation

Using Command Line

For new installations, during installation create a custom partition setup and specify a separate partition for /tmp.

For systems that were previously installed, use the Logical Volume Manager (LVM) to create partitions.

Default Value

By default, Ubuntu does not create a separate partition for /tmp.

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
• AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/

Profile

Level 1 - Scored