McAfee VIRUSSCAN 4.5 -, Administrator'S Manual

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Administrator’s Guide 23
About VirusScan Software
How does VirusScan software work?
VirusScan software combines the anti-virus industry’s most capable scan
engine with top-notch interface enhancements that give you complete access
to that engine’s power. The VirusScan graphical user interface unifies its
specialized program components, but without sacrificing the flexibility you
need to fit the software into your computing environment. The scan engine,
meanwhile, combines the best features of technologies that McAfee and Dr
Solomon researchers developed independently for more than a decade.
Fast, accurate virus detection
The foundation for that combination is the unique development environment
that McAfee and Dr Solomon researchers constructed for the engine. That
environment includes Virtran, a specialized programming language with a
structure and “vocabulary” optimized for the particular requirements that
virus detection and removal impose. Using specific library functions from this
language, for instance, virus researchers can pinpoint those sections within a
file, a boot sector, or a master boot record that viruses tend to infect, either
because they can hide within them, or because they can hijack their execution
routines. This way, the scanner avoids having to examine the entire file for
virus code; it can instead sample the file at well defined points to look for virus
code signatures that indicate an infection.
The development environment brings as much speed to .DAT file construction
as it does to scan engine routines. The environment provides tools researchers
can use to write “generic” definitions that identify entire virus families, and
that can easily detect the tens or hundreds of variants that make up the bulk of
new virus sightings. Continual refinements to this technique have moved
most of the hand-tooled virus definitions that used to reside in .DAT file
updates directly into the scan engine as bundles of generic routines.
Researchers can even employ a Virtran architectural feature to plug in new
engine “verbs” that, when combined with existing engine functions, can add
functionality needed to deal with new infection techniques, new variants, or
other problems that emerging viruses now pose.
This results in blazingly quick enhancements the engine’s detection
capabilities and removes the need for continuous updates that target virus
variants.
Encrypted polymorphic virus detection
Along with generic virus variant detection, the scan engine now incorporates
a generic decryption engine, a set of routines that enables VirusScan software
to track viruses that try to conceal themselves by encrypting and mutating
their code signatures. These “polymorphic” viruses are notoriously difficult to
detect, since they change their code signature each time they replicate.