The detection rule 'GCP Service Account Disabled' is designed to identify when a service account in Google Cloud Platform (GCP) is disabled. Service accounts are non-human accounts used for applications and virtual machine (VM) instances to make authorized API calls. Disabling these accounts can disrupt business operations, making this rule crucial for security monitoring. The detection leverages audit logs to correlate specific event actions—namely the DisableServiceAccount action—and their outcomes. False positives may arise from legitimate system administrator actions, necessitating confirmation of expected behavior or the potential need for exceptions in cases of routine maintenance or automated scripts. The rule establishes detailed thresholds for audit log review and investigation strategies following a detection, including checking actor identity, reviewing permission modifications, and assessing impacts on associated services. Recommendations for incident response are provided, emphasizing immediate actions like revoking permissions of the affected account, re-enabling it if deemed legitimate, and further enhancing monitoring and examinations of security practices surrounding service accounts.