Automatic Patch-Based Exploit Generation can mean that an attacker can simply wait for a patch to be released, use these techniques, and with reasonable chance, produce a working exploit within seconds. Coupled with a worm, all vulnerable hosts could be compromised before most are even aware a patch is available, let alone download it. Thus, Microsoft should redesign Windows Update. We propose solutions which prevent several possible schemes, some of which could be done with existing technology.

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http://www.cs.cmu.edu/~dbrumley/pubs/apeg.html