Limiting MitM to MitE Covert-Channels

Abstract

We study covert channels between a MitM attacker, and her MitE 'malware', running within the protected network of a victim organisation, and how to prevent or limit such channels. Our focus is on advanced timing channels, that allow communication between the MitM and MitE, even when hosts inside the protected network are restricted to only communicate to other (local and remote) hosts in the protected network. Furthermore, we assume communication is encrypted with fixed packet size (padding). We show that these do not suffice to prevent covert channels between MitM and MitE; furthermore, we show that even if we restrict communication to a constant rate, e.g., one packet everysecond, communication from MitE to MitM is still possible.We present efficient traffic shapers against covert channels between MitM and MitE. Our solutions preserve efficiency and bounded delay (QoS), while limiting covert traffic leakage, in both directions.