Vulnerability Discussion

The macOS must be configured to enforce a minimum password lifetime limit of 24 hours.

This rule discourages users from cycling through their previous passwords to get back to a preferred one.

Note: The guidance for password-based authentication in NIST 800-53 (Rev 5) and NIST 800-63B state that complexity rules should be organizationally defined. The values defined are based on common complexity values, but an organization may define its own password complexity rules.

Check

Verify the macOS system is configured to set minimum password lifetime to 24 hours with the following command:

/usr/bin/pwpolicy -getaccountpolicies 2> /dev/null | /usr/bin/tail +2 | /usr/bin/xmllint --xpath '//dict/key[text()="policyAttributeMinimumLifetimeHours"]/following-sibling::integer[1]/text()' - | /usr/bin/awk '{ if ($1 >= 24 ) {print "yes"} else {print "no"}}'

If the result is not "yes", this is a finding.

Fix

Configure the macOS system to set minimum password lifetime to 24 hours.

This setting may be enforced using local policy or by a directory service.

To set local policy to require a minimum password lifetime, edit the current password policy to contain the following within the "policyCategoryPasswordContent":

[source,xml]
----

policyContent
policyAttributeLastPasswordChangeTime < policyAttributeCurrentTime - (policyAttributeMinimumLifetimeHours * 60 * 60)
policyIdentifier
Minimum Password Lifetime
policyParameters

policyAttributeMinimumLifetimeHours
24


----
After saving the file and exiting to the command prompt, run the following command to load the new policy file, substituting the path to the file in place of "$pwpolicy_file".

[source,bash]
----
/usr/bin/pwpolicy setaccountpolicies $pwpolicy_file
----
Note: Refer to the password policy supplemental on more information on how to implement password policies on macOS.