cis-ubuntu2004-v300-5-3-3-2-6

DevOps & Security

Ensure password dictionary check is enabled

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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-v300-5-3-3-2-6/SKILL.md

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5.3.3.2.6 Ensure password dictionary check is enabled (Automated)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

The pwquality dictcheck option sets whether to check for the words from the cracklib dictionary.

Rationale

If the operating system allows the user to select passwords based on dictionary words, this increases the chances of password compromise by increasing the opportunity for successful guesses, and brute-force attacks.

Audit Procedure

Command Line

Run the following command to verify that the dictcheck option is not set to 0 (disabled) in a pwquality configuration file:

# grep -Psi -- '^\h*dictcheck\h*=\h*0\b' /etc/security/pwquality.conf /etc/security/pwquality.conf.d/*.conf

Nothing should be returned.

Run the following command to verify that the dictcheck option is not set to 0 (disabled) as a module argument in a PAM file:

# grep -Psi -- '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\r]+\h+)?dictcheck\h*=\h*0\b' /etc/pam.d/common-password

Nothing should be returned.

Note:

Settings observe an order of precedence:
- module arguments override the settings in the /etc/security/pwquality.conf configuration file
- settings in the /etc/security/pwquality.conf configuration file override settings in a .conf file in the /etc/security/pwquality.conf.d/ directory
- settings in a .conf file in the /etc/security/pwquality.conf.d/ directory are read in canonical order, with last read file containing the setting taking precedence
It is recommended that settings be configured in a .conf file in the /etc/security/pwquality.conf.d/ directory for clarity, convenience, and durability.

Remediation

Command Line

Edit any file ending in .conf in the /etc/security/pwquality.conf.d/ directory and/or the file /etc/security/pwquality.conf and comment out or remove any instance of dictcheck = 0:

Example:

# sed -ri 's/^\s*dictcheck\s*=/#  &/' /etc/security/pwquality.conf /etc/security/pwquality.conf.d/*.conf

Run the following command:

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

Edit any returned files and remove the dictcheck argument from the pam_pwquality.so line(s).

Default Value

dictcheck = 1

References

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

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	5.2 Use Unique Passwords	*	*	*
v7	4.4 Use Unique Passwords		*	*

MITRE ATT&CK Mappings

Techniques / Sub-techniques	Tactics	Mitigations
T1110, T1110.001, T1110.002, T1110.003, T1178.001, T1178.002, T1178.003, T1178.004	TA0006	M1027