Consider: Malware that doesn't do anything suspicious unless it can first fetch a plausible benign file from what looks like a CDN. If the goal is to properly inspect the behaviour of potentially-malicious code, what it does after successfully fetching a set of ads is as, if not more important than what it does when the connection is blocked. Perhaps a multiplayer game with a backdoor triggered by the MotD service, through intentionally-vulnerable-to-buffer-overflows string processing code.