[PCI DSS 3.0] 5.3 Ensure that anti-virus mechanisms are actively running and cannot be disabled or altered by user

5.3 Ensure that anti-virus mechanisms are actively running and cannot be disabled or altered by users, unless specifically authorized by management on a case-by-case basis for a limited time period.

Note: Anti-virus solutions may be temporarily disabled only if there is legitimate technical need, as authorized by management on a case-by-case basis. If anti-virus protection needs to be disabled for a specific purpose, it must be formally authorized. Additional security measures may also need to be
implemented for the period of time during which anti-virus protection is not active.

5.3.a Examine anti-virus configurations, including the master installation of the software and a sample of system
components, to verify the anti-virus software is actively running.

5.3.b Examine anti-virus configurations, including the master installation of the software and a sample of system components, to verify that the anti-virus software cannot be disabled or altered by users.

5.3.c Interview responsible personnel and observe processes to verify that anti-virus software cannot be disabled or altered by users, unless specifically authorized by management on a
case-by-case basis for a limited time period.

Anti-virus that continually runs and is unable to be altered will provide persistent security against malware.
Use of policy-based controls on all systems to ensure anti-malware protections cannot be altered or disabled will help prevent system weaknesses from being exploited by malicious software.
Additional security measures may also need to be implemented for the period of time during which anti-virus protection is not active—for example, disconnecting the unprotected system from the Internet while the anti-virus protection is disabled, and running a full scan after it is re-enabled.