Controls related to authorized modifications to production programs are best tested by tracing modifications from the original request for change forward to the executable program, as this ensures that the change management process was followed and that the modifications were approved, documented, tested, and implemented correctly. Tracing modifications from the executable program back to the original request for change may not reveal any unauthorized or undocumented changes that occurred during the process. Testing only the authorizations to implement the new program or reviewing only the actual lines of source code changed in the program are not sufficient to test the controls related to authorized modifications, as they do not cover the entire change management process. References: CISA Review Manual (Digital Version), Chapter 4: Information Systems Operations, Maintenance and Service Management, Section 4.2: Change Management

ACloud Access Security Broker (CASB)ensuresvisibility, compliance, and securityof cloud applications, andmonitoring data movementis the key to detecting threats.
Option A (Correct):Monitoring data movementallows organizations todetect and preventunauthorized access, data exfiltration, and cloud-based threats.
Option B (Incorrect):Along-term contractdoes not inherentlyimprove security monitoring.
Option C (Incorrect):Reviewing policies helps withgovernance, but it does notactively detect threats.
Option D (Incorrect):Firewallsprotectnetwork perimeters, while CASBs focus oncloud security, making this anineffective measurefor CASB threat detection.
Reference:ISACA CISA Review Manual -Domain 5: Protection of Information Assets- CoversCASB, cloud security, and threat detection best practices.

The most effective method to verify that a service vendor keeps control levels as required by the client is to conduct periodic on-site assessments using agreed-upon criteria. On-site assessments can provide direct evidence of whether the vendor's controls are operating effectively and consistently in accordance with the client's expectations and requirements. Agreed-upon criteria can ensure that the assessments are objective, relevant, and reliable. The other options are not as effective as on-site assessments in verifying the vendor's control levels. Periodically reviewing the SLA with the vendor can help monitor whether the vendor meets its contractual obligations and service standards, but it does not provide assurance of whether the vendor's controls are adequate or sufficient. Conducting an unannounced vulnerability assessment of vendor's IT systems can help identify any weaknesses or gaps in the vendor's security controls, but it may violate the terms and conditions of the vendor-client relationship or cause operational disruptions. Obtaining evidence of the vendor's CSA can provide some indication of whether the vendor's controls are self-monitored and reported, but it does not verify whether the vendor's controls are independent or accurate. References: CISA Review Manual (Digital Version), Chapter 5, Section 5.4