This analytic rule detects modifications to default Group Policy Objects (GPOs) related to Windows security through monitoring Windows Event Log Security, specifically Event ID 5136. It focuses on changes to two key policies: the `Default Domain Controllers Policy` and the `Default Domain Policy`. These GPOs play a critical role in the security configuration of a Windows domain, controlling settings applied to all domain users and computers. Unauthorized changes to these policies may indicate a security breach, where an attacker with privileged access attempts to compromise the network by deploying persistent threats or malware. Such modifications, if confirmed as malicious, could facilitate significant control over multiple hosts within the network, leading to a broader compromise. The detection rule requires the `Audit Directory Service Changes` setting to be enabled for proper function, and it is recommended to implement required SACLs for enhanced monitoring capabilities.