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5.2.6 Ensure password expiration is configured

Information

The maximum password age attribute ( maxage ) determines the maximum number of weeks that you can use a password before you must change it.

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.

We recommend a yearly password change. This is primarily because for all their good intentions users will share credentials across accounts. Therefore, even if a breach is publicly identified, the user may not see this notification, or forget they have an account on that site. This could leave a shared credential vulnerable indefinitely. Having an organizational policy of a 1-year (annual) password expiration is a reasonable compromise to mitigate this with minimal user burden.

Solution

In /etc/security/user, set the default user stanza maxage attribute to a number greater than 0 but less than or equal to 52 that follows local site policy:

chsec -f /etc/security/user -s default -a maxage=52

This means that a user password must be changed 52 weeks after being set. If 0 is set then this effectively disables password ageing.

Impact:

The password expiration must be greater than the minimum days between password changes or users will be unable to change their password.

Excessive password expiration requirements do more harm than good, because these requirements make users select predictable passwords, composed of sequential words and numbers that are closely related to each other. In these cases, the next password can be predicted based on the previous one (incrementing a number used in the password for example). Also, password expiration requirements offer no containment benefits because attackers will often use credentials as soon as they compromise them. Instead, immediate password changes should be based on key events including, but not limited to:

 -
Indication of compromise

 -
Change of user roles

 -
When a user leaves the organization.

Not only does changing passwords every few weeks or months frustrate the user, but it's also been suggested that it does more harm than good, because it could lead to bad practices by the user such as adding a character to the end of their existing password.

See Also

https://workbench.cisecurity.org/benchmarks/22751

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

References: 800-53|IA-5(1), CSCv7|4.4

Plugin: Unix

Control ID: 6ef1b4cb0ced7db0692e20587471ad8ffdba225a00c08c371f08c22050d9993c