cis-ubuntu1804-v220-4-3-6

name	cis-ubuntu1804-v220-4-3-6
description	Ensure sudo authentication timeout is configured correctly
category	cis-iam
version	2.2.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-18.04","sudo","privilege-escalation"]
cis_id	4.3.6
cis_benchmark	CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 4.3.6

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Description

sudo caches credentials for a period of time. The default timeout for the sudo command is 15 minutes. It is recommended that the timeout be set to no more than 15 minutes.

Rationale

If the timeout is too long, a user could execute commands as root for an extended period without re-authenticating. This could allow unauthorized users to execute commands as root if the original user walks away from their terminal.

Audit Procedure

Command Line

Run the following command to verify the sudo authentication timeout:

grep -roP "timestamp_timeout\h*=\h*\d+" /etc/sudoers /etc/sudoers.d/

Expected Result

If output is returned, timestamp_timeout should be 15 or less. If no output is returned, the default of 15 minutes is in effect, which is compliant.

Remediation

Command Line

Edit the file /etc/sudoers or a file in /etc/sudoers.d/ with visudo and set or modify the timestamp_timeout value:

Defaults timestamp_timeout=15

OR set to a value of 15 or less per site policy.

Default Value

timestamp_timeout=15

References

1. NIST SP 800-53 Rev. 5: IA-11

CIS Controls

v8 - 5.4 Restrict Administrator Privileges to Dedicated Administrator Accounts.

v7 - 4.3 Ensure the Use of Dedicated Administrative Accounts.

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Assessment Status

Automated