CIS Ubuntu 14.04 LTS - 5.4.1.1 Ensure password expiration is 365 days or less

DevOps & Security

Verify PASS_MAX_DAYS is set to 365 or less in /etc/login.defs for password expiration

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5.4.1.1 Ensure password expiration is 365 days or less (Scored)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

The PASS_MAX_DAYS parameter in /etc/login.defs allows an administrator to force passwords to expire once they reach a defined age. It is recommended that the PASS_MAX_DAYS parameter be set to less than or equal to 365 days.

Rationale

The window of opportunity for an attacker to leverage compromised credentials or successfully compromise credentials via an online brute force attack is limited by the age of the password. Therefore, reducing the maximum age of a password also reduces an attacker's window of opportunity.

Audit Procedure

Run the following command and verify PASS_MAX_DAYS conforms to site policy (no more than 365 days):

grep PASS_MAX_DAYS /etc/login.defs

Verify all users with a password maximum days between password change conforms to site policy (no more than 365 days):

egrep ^[^:]+:[^\!*] /etc/shadow | cut -d: -f1
chage --list <user>

Expected Result

PASS_MAX_DAYS 90
Maximum number of days between password change          : 90

Remediation

Set the PASS_MAX_DAYS parameter to conform to site policy in /etc/login.defs:

PASS_MAX_DAYS 90

Modify user parameters for all users with a password set to match:

chage --maxdays 90 <user>

Default Value

PASS_MAX_DAYS 99999

References

CIS Controls: 16 - Account Monitoring and Control

Profile

Level 1 - Server
Level 1 - Workstation