Non-DNS Traffic Using Port 53 for C2 Evasion
This rule detects non-DNS traffic attempting to use port 53, which is typically reserved for DNS queries. This behavior is often indicative of command and control (C2) evasion techniques, where attackers tunnel their C2 communications over a commonly allowed port to bypass firewalls and network monitoring. The rule specifically looks for TCP traffic to port 53 that is not identified as DNS application-layer protocol, originating from the home network, and establishes a flow. A threshold of 5 such events within 30 seconds from the same source IP triggers the alert.
Suricata
