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Showing posts from February, 2008

Cooperating Detectors

A malware detector tries to determine whether a program is malicious (examples
of malicious programs are drive-by-downloads, botnets, and keyloggers).
Malware detection is primarily performed at two vantage points: host and
network. This post explains why cooperation between host-based and network-
based detectors is a good thing.

Traditionally, detection has been performed either at the network or host level, but
not both. First, let me examine both approaches separately.

A network-based detector monitors events by examining a session or
network flow and tries to determine whether it is malicious. The
advantage of a network-based detector is ease of deployment -- there
are not that many points of deployment for a network-based detector
(typically they are deployed behind border routers).

Unfortunately, network-based detectors have a limited view of each
network session. In fact, if a session happens to be
encrypted such as is common with VPNs, Skype, and some bots, a
network-based detector is esse…