Kaspersky researchers have discovered PhantomRPC, a new Windows privilege escalation technique that exploits architectural weaknesses in the operating system's Remote Procedure Call mechanism to allow attackers to gain System-level access. The vulnerability works by deploying fake RPC servers that impersonate legitimate Windows services, intercepting requests from high-privilege processes and abusing Windows's built-in impersonation functionality. Microsoft has classified the issue as moderate severity and says it doesn't require immediate patching, as exploitation requires an attacker to first compromise a privileged service, though researchers found multiple attack paths across all Windows versions.