Cover your ACKs: Pitfalls of covert channel censorship circumvention

John Geddes, Max Schuchard, Nick Hopper

Research output: Chapter in Book/Report/Conference proceedingConference contribution

28 Scopus citations

Abstract

In response to increasingly sophisticated methods of blocking access to censorship circumvention schemes such as Tor, recently proposed systems such as Skypemorph, FreeWave, and CensorSpoofer have used voice and video conferencing protocols as "cover channels" to hide proxy connections. We demonstrate that even with perfect emulation of the cover channel, these systems can be vulnerable to attacks that detect or disrupt the covert communications while having no effect on legitimate cover traffic. Our attacks stem from differences in the channel requirements for the cover protocols, which are peer-to-peer and loss tolerant, and the covert traffic, which is client-proxy and loss intolerant. These differences represent significant limitations and suggest that such protocols are a poor choice of cover channel for general censorship circumvention schemes.

Original languageEnglish (US)
Title of host publicationCCS 2013 - Proceedings of the 2013 ACM SIGSAC Conference on Computer and Communications Security
Pages361-372
Number of pages12
DOIs
StatePublished - Dec 9 2013
Event2013 ACM SIGSAC Conference on Computer and Communications Security, CCS 2013 - Berlin, Germany
Duration: Nov 4 2013Nov 8 2013

Publication series

NameProceedings of the ACM Conference on Computer and Communications Security
ISSN (Print)1543-7221

Other

Other2013 ACM SIGSAC Conference on Computer and Communications Security, CCS 2013
CountryGermany
CityBerlin
Period11/4/1311/8/13

Keywords

  • anonymity
  • censorship
  • censorspoofer
  • freewave
  • skypemorph

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