GCP: Firewall Rule Modified [splunk-gcpaudit]

Adversaries may disable or modify a firewall within a cloud environment to bypass controls that limit access to cloud resources. Cloud environments typically utilize restrictive security groups and firewall rules that only allow network activity from trusted IP addresses via expected ports and protocols. An adversary may introduce new firewall rules or policies to allow access into a victim cloud environment. For example, an adversary may use a script or utility that creates new ingress rules in existing security groups to allow any TCP/IP connectivity. Modifying or disabling a cloud firewall may enable adversary C2 communications, lateral movement, and/or data exfiltration that would otherwise not be allowed.