Vulnerability Discussion

The macOS is able to be configured to set an automated termination for 72 hours or less for all temporary or emergency accounts upon account creation.

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 disabled, system maintenance during emergencies may not be possible, thus adversely affecting system availability.

Although the ability to create and use emergency administrator accounts is necessary for performing system maintenance during emergencies, these accounts present vulnerabilities to the system if they are not disabled and removed when they are no longer needed. Configuring the macOS to automatically remove or disable emergency accounts within 72 hours of creation mitigates the risks posed if one were to be created and accidentally left active once the crisis is resolved.

Emergency administrator accounts are different from infrequently used accounts (i.e., local logon accounts used by system administrators when network or normal logon 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 can be integrated with enterprise-level authentication/access mechanisms that meet or exceed access control policy requirements.

If temporary or emergency 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 or emergency accounts must be set to 72 hours (or less) when the temporary or emergency account is created.

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.

Satisfies: SRG-OS-000002-GPOS-00002,SRG-OS-000123-GPOS-00064

Check

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/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 "policyCategoryAuthentication".

In the array that follows, there should be a section that contains a check 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

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:


policyCategoryAuthentication


policyContent
policyAttributeCurrentTime < policyAttributeCreationTime+259299
policyIdentifier
Disable Tmp Accounts




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/pwpolicy -u username setaccountpolicies /path/to/file