This detection rule identifies instances when the Windows Defender service (WinDefend) is disabled through modifications made to the registry. Specifically, it looks for changes to the registry key that controls the startup type of the WinDefend service, detecting when it is set to a DWORD value of 4 (disabled), indicating that an attacker or malicious tool has taken steps to disable this important security feature. The rule utilizes specific characteristics of the registry change to trigger an alert and is particularly useful in environments where Windows Defender is expected to be enabled and actively protecting systems from threats. As Windows Defender is a critical component in defending against malware and other attacks, monitoring changes to its operational status is essential for maintaining overall system security and integrity.