cis-ubuntu2004-v300-5-1-13

name	cis-ubuntu2004-v300-5-1-13
description	Ensure sshd LoginGraceTime is configured
category	cis-networking
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","ssh"]
cis_id	5.1.13
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure sshd LoginGraceTime is configured (Automated)

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Description

The LoginGraceTime parameter specifies the time allowed for successful authentication to the SSH server. The longer the Grace period is the more open unauthenticated connections can exist. Like other session controls in this session the Grace Period should be limited to appropriate organizational limits to ensure the service is available for needed access.

Rationale

Setting the LoginGraceTime parameter to a low number will minimize the risk of successful brute force attacks to the SSH server. It will also limit the number of concurrent unauthenticated connections While the recommended setting is 60 seconds (1 Minute), set the number based on site policy.

Audit Procedure

Command Line

Run the following command and verify that output LoginGraceTime is between 1 and 60 seconds:

# sshd -T | grep logingracetime

logingracetime 60

Expected Result

logingracetime 60

(or a value between 1 and 60)

Remediation

Command Line

Edit the /etc/ssh/sshd_config file to set the LoginGraceTime parameter to 60 seconds or less above any Include entry as follows:

LoginGraceTime 60

Note: First occurrence of a option takes precedence. If Include locations are enabled, used, and order of precedence is understood in your environment, the entry may be created in a file in Include location.

Default Value

LoginGraceTime 120

References

1. SSHD_CONFIG(5)
2. NIST SP 800-53 Rev. 5: CM-6
3. SSHD(8)

CIS Controls

v8 - 0.0 Explicitly Not Mapped

v7 - 0.0 Explicitly Not Mapped

MITRE ATT&CK Mappings: T1110, T1110.001, T1110.003, T1110.004 | TA0006 | M1036