cis-ubuntu2004-v300-5-3-3-1-3

DevOps & Security

Ensure password failed attempts lockout includes root account

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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-v300-5-3-3-1-3/SKILL.md

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5.3.3.1.3 Ensure password failed attempts lockout includes root account (Automated)

Profile Applicability

Level 2 - Server
Level 2 - Workstation

Description

even_deny_root - Root account can become locked as well as regular accounts.

root_unlock_time=n - This option implies even_deny_root option. Allow access after n seconds to root account after the account is locked. In case the option is not specified the value is the same as of the unlock_time option.

Rationale

Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute force password attacks against your systems.

Impact

Use of unlock_time=0 or root_unlock_time=0 may allow an attacker to cause denial of service to legitimate users.

Audit Procedure

Command Line

Run the following command to verify that even_deny_root and/or root_unlock_time is enabled:

# grep -Pi -- '^\h*(even_deny_root|root_unlock_time\h*=\h*\d+)\b' /etc/security/faillock.conf

Example output:

even_deny_root

--AND/OR--

root_unlock_time = 60

Run the following command to verify that - IF - root_unlock_time is set, it is set to 60 (One minute) or more:

# grep -Pi -- '^\h*root_unlock_time\h*=\h*([1-9]|[1-5][0-9])\b' /etc/security/faillock.conf

Nothing should be returned.

Run the following command to check the pam_faillock.so module for the root_unlock_time argument. Verify -IF- root_unlock_time is set, it is set to 60 (One minute) or more:

# grep -Pi -- '^\h*auth\h+([^#\n\r]+\h+)pam_faillock\.so\h+([^#\n\r]+\h+)?root_unlock_time\h*=\h*([1-9]|[1-5][0-9])\b' /etc/pam.d/common-auth

Nothing should be returned.

Remediation

Command Line

Edit /etc/security/faillock.conf:

Remove or update any line containing root_unlock_time, - OR - set it to a value of 60 or more
Update or add the following line:

even_deny_root

Run the following command:

# grep -Pl -- '\bpam_faillock\.so\h+([^#\n\r]+\h+)?(even_deny_root|root_unlock_time)' /usr/share/pam-configs/*

Edit any returned files and remove the even_deny_root and root_unlock_time arguments from the pam_faillock.so line(s).

Default Value

disabled

Additional Information

If a user has been locked out because they have reached the maximum consecutive failure count defined by deny= in the pam_faillock.so module, the user can be unlocked by issuing the command faillock --user <USERNAME> --reset. This command sets the failed count to 0, effectively unlocking the user.

References

None listed.

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	6.2 Establish an Access Revoking Process	*	*	*
v7	16.7 Establish Process for Revoking Access		*	*

MITRE ATT&CK Mappings

Techniques / Sub-techniques	Tactics	Mitigations
T1110, T1110.001, T1110.003	TA0006	M1027