DDoS Defense by Offense

Michael Walfish, Mythili Vutukuru, Hari Balakrishnan, David Karger, Scott Shenker
ACM SIGCOMM 2006, Pisa, Italy, September 2006

This paper presents the design, implementation, analysis, and experimental evaluation of speak-up, a defense against application-level distributed denial-of-service (DDoS), in which attackers cripple a server by sending legitimate-looking requests that consume computational resources (e.g., CPU cycles, disk). With speak-up, a victimized server encourages all clients, resources permitting, to automatically send higher volumes of traffic. We suppose that attackers are already using most of their upload bandwidth so cannot react to the encouragement. Good clients, however, have spare upload bandwidth and will react to the encouragement with drastically higher volumes of traffic. The intended outcome of this traffic inflation is that the good clients crowd out the bad ones, thereby capturing a much larger fraction of the server's resources than before. We experiment under various conditions and find that speak-up causes the server to spend resources on a group of clients in rough proportion to their aggregate upload bandwidth. This result makes the defense viable and effective for a class of real attacks.

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Bibtex Entry:

@inproceedings{walfish2006ddos,
   author =       "Michael Walfish and Mythili Vutukuru and Hari Balakrishnan and David Karger and Scott Shenker",
   title =        "{DDoS Defense by Offense}",
   booktitle =    {ACM SIGCOMM 2006},
   year =         {2006},
   month =        {September},
   address =      {Pisa, Italy}
}