The first action should be to reset access for John and Joe, who are corporate accounts belonging to the organization. Their credentials were exposed in recent leaks, including one from an initial access broker (Joe), which indicates an active exploitation risk. Immediate password resets and session invalidations prevent adversaries from using the compromised credentials to gain access.

Ann’s account (@hotmail.com) is personal and not under corporate management, so while her exposure is concerning, it does not pose a direct risk to organizational systems. Contacting her can follow later steps but should not delay urgent remediation for John and Joe.

Option B delays remediation. Option C overreaches by including Ann in corporate resets. Option D includes contacting authorities prematurely, which is important but secondary to immediate containment.

CAS-005 emphasizes rapid containment of credential leaks affecting corporate identities, making access resets for John and Joe the first step.