Researchers have demonstrated a new way to hide secret messages in internet traffic that can elude even vigilant network operators.
The paper presents a new steganographic method called RSTEG
(Retransmission Steganography), which is intended for a broad class of protocols that
utilises retransmission mechanisms. The main innovation of RSTEG is to not
acknowledge a successfully received packet in order to intentionally invoke
retransmission. The retransmitted packet carries a steganogram instead of user data in
the payload field. RSTEG is presented in the broad context of network steganography,
and the utilisation of RSTEG for TCP (Transport Control Protocol) retransmission
mechanisms is described in detail. Simulation results are also presented with the main
aim to measure and compare the steganographic bandwidth of the proposed method for
different TCP retransmission mechanisms as well as to determine the influence of
RSTEG on the network retransmissions level.