cis-ubuntu2004-v300-5-1-20

DevOps & Security

Ensure sshd PermitRootLogin is disabled

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_20.04_LTS_Benchmark_v3.0.0/cis-ubuntu2004-v300-5-1-20/SKILL.md

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Ensure sshd PermitRootLogin is disabled (Automated)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

The PermitRootLogin parameter specifies if the root user can log in using SSH. The default is prohibit-password.

Rationale

Disallowing root logins over SSH requires system admins to authenticate using their own individual account, then escalating to root. This limits opportunity for non-repudiation and provides a clear audit trail in the event of a security incident.

Audit Procedure

Command Line

Run the following command to verify PermitRootLogin is set to no:

# sshd -T | grep permitrootlogin

permitrootlogin no

IF - Match set statements are used in your environment, specify the connection parameters to use for the -T extended test mode and run the audit to verify the setting is not incorrectly configured in a match block. Example additional audit needed for a match block for the user sshuser:

# sshd -T -C user=sshuser | grep permitrootlogin

Note: If provided, any Match directives in the configuration file that would apply are applied before the configuration is written to standard output. The connection parameters are supplied as keyword=value pairs and may be supplied in any order, either with multiple -C options or as a comma-separated list. The keywords are addr (source address), user (user), host (resolved source host name), laddr (local address), lport (local port number), and rdomain (routing domain)

Expected Result

permitrootlogin no

Remediation

Command Line

Edit the /etc/ssh/sshd_config file to set the PermitRootLogin parameter to no above any Include and Match entries as follows:

PermitRootLogin no

Note: First occurrence of an option takes precedence, Match set statements withstanding. 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

PermitRootLogin without-password

References

SSHD_CONFIG(5)
NIST SP 800-53 Rev. 5:AC-6

CIS Controls

v8 - 5.4 Restrict Administrator Privileges to Dedicated Administrator Accounts Restrict administrator privileges to dedicated administrator accounts on enterprise assets. Conduct general computing activities, such as internet browsing, email, and productivity suite use, from the user's primary, non-privileged account.

v7 - 4.3 Ensure the Use of Dedicated Administrative Accounts Ensure that all users with administrative account access use a dedicated or secondary account for elevated activities. This account should only be used for administrative activities and not internet browsing, email, or similar activities.

MITRE ATT&CK Mappings: T1021 | TA0008 | M1042