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name: cis-ubuntu1204-v110-2-3 description: "Set nosuid option for /tmp Partition" category: cis-os-hardening version: "1.1.0" author: cyberstrike-official tags: [cis, ubuntu, 12.04, linux, filesystem, tmp, nosuid, mount-options] cis_id: "2.3" cis_benchmark: "CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0" tech_stack: [ubuntu, linux] cwe_ids: [] chains_with: [] prerequisites: [] severity_boost: {}

2.3 Set nosuid option for /tmp Partition (Scored)

Profile Applicability

• Level 1

Description

The nosuid mount option specifies that the filesystem cannot contain set userid files.

Rationale

Since the /tmp filesystem is only intended for temporary file storage, set this option to ensure that users cannot create set userid files in /tmp.

Audit Procedure

Using Command Line

grep /tmp /etc/fstab | grep nosuid
mount | grep /tmp | 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). See the fstab(5) manual page for more information.

mount -o remount,nosuid /tmp

Default Value

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

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Scored