Date Added: Mar 2012
As the number and complexity of attacks on computer systems are increasing, this growth necessitates proper defense mechanisms. Intrusion detection systems play an important role in detecting and disrupting attacks before they can compromise software. Multivariant execution is an intrusion detection mechanism that executes several slightly different versions, called variants, of the same program in lockstep. The variants are built to have identical behavior under normal execution conditions. However, when the variants are under attack, there are detectable differences in their execution behavior. At runtime, a monitor compares the behavior of the variants at certain synchronization points and raises an alarm when a discrepancy is detected.