The vulnerabilities which plague computers cause endless grief to users. Slammer compromised millions of hosts in minutes; a hit-list worm would take under a second. Recently proposed techniques respond better than manual approaches, but require expensive instrumentation, limiting deployment. Although spreading “antibodies” (e.g. signatures) ameliorates this limitation, hosts dependant on antibodies are defenseless until inoculation; to the fastest hit-list worms this delay is crucial. Additionally, most recently proposed techniques cannot provide recovery to provide continuous service after an attack. We propose a solution, called Sweeper, that provides both fast and accurate post-attack analysis and efficient recovery with low normal execution overhead. Sweeper combines several techniques. (1) Sweeper uses lightweight monitoring techniques to detect a wide array of suspicious requests, providing a first level of defense. (2) By leveraging lightweight checkpointing, Sweeper post...