Title

The macOS system must automatically remove or disable temporary and emergency user accounts after 72 hours. (Cat II impact)

Discussion

If temporary user accounts remain active when no longer needed or for an excessive period, these accounts may be targeted by attackers to gain unauthorized access. To mitigate this risk, automated termination of all temporary accounts must be set upon account creation. Temporary accounts are established as part of normal account activation procedures when there is a need for short-term accounts without the demand for immediacy in account activation. If temporary accounts are used, the operating system must be configured to automatically terminate these types of accounts after a DoD-defined time period of 72 hours. Emergency administrator accounts are privileged accounts established in response to crisis situations where the need for rapid account activation is required. Therefore, emergency account activation may bypass normal account authorization processes. If these accounts are automatically disabled, system maintenance during emergencies may not be possible, thus adversely affecting system availability. Emergency administrator accounts are different from infrequently used accounts (i.e., local logon accounts used by system administrators when network or normal logon/access is not available). Infrequently used accounts also remain available and are not subject to automatic termination dates. However, an emergency administrator account is normally a different account created for use by vendors or system maintainers. To address access requirements, many operating systems may be integrated with enterprise-level authentication/access mechanisms that meet or exceed access control policy requirements. Satisfies: SRG-OS-000002-GPOS-00002, SRG-OS-000123-GPOS-00064

Check Content

Verify if a password policy is enforced by a directory service by asking the System Administrator (SA) or Information System Security Officer (ISSO). If no policy is enforced by a directory service, a password policy can be set with the "pwpolicy" utility. The variable names may vary depending on how the policy was set. If there are no temporary or emergency accounts defined on the system, this is Not Applicable. To check if the password policy is configured to disable a temporary or emergency account after 72 hours, run the following command to output the password policy to the screen, substituting the correct user name in place of username: /usr/bin/sudo /usr/bin/pwpolicy -u username getaccountpolicies | tail -n +2 If there is no output, and password policy is not controlled by a directory service, this is a finding. Otherwise, look for the line "<key>policyCategoryAuthentication</key>". In the array that follows, there should be a <dict> section that contains a check <string> that allows users to log in if "policyAttributeCurrentTime" is less than the result of adding "policyAttributeCreationTime" to 72 hours (259299 seconds). The check might use a variable defined in its "policyParameters" section. If the check does not exist or if the check adds too great an amount of time to "policyAttributeCreationTime", this is a finding.

Fix Text

This setting may be enforced using local policy or by a directory service. To set local policy to disable a temporary or emergency user, create a plain text file containing the following: <dict> <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>policyAttributeCurrentTime &lt; policyAttributeCreationTime+259299</string> <key>policyIdentifier</key> <string>Disable Tmp Accounts </string> </dict> </array> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file, substituting the correct user name in place of "username" and the path to the file in place of "/path/to/file". /usr/bin/sudo /usr/bin/pwpolicy -u username setaccountpolicies /path/to/file

Additional Identifiers

Rule ID: SV-252444r816146_rule

Vulnerability ID: V-252444

Group Title: SRG-OS-000002-GPOS-00002

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.