Covert Communication using Address Resolution Protocol Broadcast Request Messages

A covert channel is a hidden communication channel that is used to transfer information in a way that breaks the security policy of a system. A Network covert channel uses network protocols to send the secret information. In this paper, a technique for Network covert communication is proposed that uses Address Resolution Protocol (ARP) Broadcast Request messages to communicate covertly over a Local Area Network. The proposed technique uses a common seed value already known to both the sender and receiver to encode the secret data and thereby strengthening the imperceptibility of the secret message. The proposed technique is robust against traffic normalization and is also resilient to frequency analysis based decoding techniques. Further, it offers a covert capacity of 7 bits per ARP Broadcast Request packet.