Infranet: Circumventing Web Censorship and Surveillance

Nick Feamster, Magdalena Balazinska, Greg Harfst, Hari Balakrishnan, David Karger
11th USENIX Security Symposium, San Francisco, CA, August 2002

Best Student Paper Award

An increasing number of countries and companies routinely block or monitor access to parts of the Internet. To counteract these measures, we propose Infranet, a system that enables clients to surreptitiously retrieve sensitive content via cooperating Web servers distributed across the global Internet. These Infranet servers provide clients access to censored sites while continuing to host normal uncensored content. Infranet uses a tunnel protocol that provides a covert communication channel between its clients and servers, modulated over standard HTTP transactions that resemble innocuous Web browsing. In the upstream direction, Infranet clients send covert messages to Infranet servers by associating meaning to the sequence of HTTP requests being made. In the downstream direction, Infranet servers return content by hiding censored data in uncensored images using steganographic techniques. We describe the design, a prototype implementation, security properties, and performance of Infranet. Our security analysis shows that Infranet can successfully circumvent several sophisticated censoring techniques.

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Bibtex Entry:

   author =       "Nick Feamster and Magdalena Balazinska and Greg Harfst and Hari Balakrishnan and David Karger",
   title =        "{Infranet: Circumventing Web Censorship and Surveillance}",
   booktitle =    {11th USENIX Security Symposium},
   year =         {2002},
   month =        {August},
   address =      {San Francisco, CA}