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

DevOps & Security

Ensure password failed attempts lockout is configured

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

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5.3.3.1.1 Ensure password failed attempts lockout is configured (Automated)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

The deny=<n> option will deny access if the number of consecutive authentication failures for this user during the recent interval exceeds.

Rationale

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

Audit Procedure

Command Line

Run the following command to verify that Number of failed logon attempts before the account is locked is no greater than 5 and meets local site policy:

# grep -Pi -- '^\h*deny\h*=\h*[1-5]\b' /etc/security/faillock.conf

Expected output:

deny = 5

Run the following command to verify that the deny argument has not been set, or 5 or less and meets local site policy:

# grep -Pi -- '^\h*auth\h+(requisite|required|sufficient)\h+pam_faillock\.so\h+([^#\n\r]+\h+)?deny\h*=\h*(0|[6-9]|[1-9][0-9]+)\b' /etc/pam.d/common-auth

Expected Result

Nothing should be returned from the second command.

Remediation

Command Line

Create or edit the following line in /etc/security/faillock.conf setting the deny option to 5 or less:

deny = 5

Run the following command:

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

Edit any returned files and remove the deny=<N> arguments from the pam_faillock.so line(s).

Default Value

deny = 3

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