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Host-based detection of worms through peer-to-peer cooperation

We propose a host-based, runtime defense against worms that achieves negligible risk of false positives through peer-to-peer cooperation. We view correlation among otherwise independent peers' behavior as anomalous behavior, indication of a fast-spreading worm. We detect correlation by exploiting worms' temporal consistency, similarity (low temporal variance) in worms' invocations of system calls. We evaluate our ideas on Windows XP with Service Pack 2 using traces of nine variants of worms and twenty-five non-worms, including ten commercial applications and fifteen processes native to the platform. We find that two peers, upon exchanging snapshots of their internal behavior, defined with frequency distributions of system calls, can decide that they are, more likely than not, executing a worm between 76% and 97% of the time. More importantly, we find that the probability that peers might err, judging a non-worm a worm, is negligible.