cis-ubuntu1204-v110-2-15

name	cis-ubuntu1204-v110-2-15
description	Add nosuid Option to /run/shm Partition
category	cis-os-hardening
version	1.1.0
author	cyberstrike-official
tags	["cis","ubuntu",12.04,"linux","filesystem","shared-memory","nosuid","mount-options"]
cis_id	2.15
cis_benchmark	CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

2.15 Add nosuid Option to /run/shm Partition (Scored)

Profile Applicability

• Level 1

Description

The nosuid mount option specifies that the /run/shm (temporary filesystem stored in memory) will not execute setuid and setgid on executable programs as such, but rather execute them with the uid and gid of the user executing the program.

Rationale

Setting this option on a file system prevents users from introducing privileged programs onto the system and allowing non-root users to execute them.

Audit Procedure

Using Command Line

grep /run/shm /etc/fstab | grep nosuid
mount | grep /run/shm | grep nosuid

Expected Result

Both commands should return output showing nosuid is set. If either command emits no output then the system is not configured as recommended.

Remediation

Using Command Line

Edit the /etc/fstab file and add nosuid to the fourth field (mounting options). Look for entries that have mount points that contain /run/shm. See the fstab(5) manual page for more information.

mount -o remount,nosuid /run/shm

Default Value

By default, the nosuid option is not set on the /run/shm partition.

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Scored