The GCP Firewall Rule Deletion detection rule monitors and alerts on the deletion of firewall rules within Google Cloud Platform (GCP). These firewall rules are critical for controlling the network traffic and ensuring the security of Virtual Private Cloud (VPC) environments or App Engine applications. Attackers may delete these rules to evade security measures, potentially allowing unauthorized access or data exfiltration. The rule utilizes GCP audit logs to identify deletion activities, flagging these events to detect any suspicious behavior that may indicate a breach. The detection logic uses KQL to query specific deletion actions and the rule is designed to operate in production environments. False positives can occur during legitimate administrative actions or routine maintenance; thus, it is recommended to establish exceptions for known safe operations. In case of a detection, the prescribed response actions include isolating affected resources, reviewing logs to ascertain the scope of the deletion, and implementing enhanced monitoring practices.