Network attacks are increasing both in sheer number as well as complexity. In recent news,
we have seen how viruses, worms and other attacks can cause major business disruptions and
cost companies worldwide billions of dollars. For instance, the Blaster worm infected over 1.2
million computers worldwide, and the SoBig.F virus infected over 100,000 computers1.
Viruses and worms are all examples of what are generally known as malicious programs or
malware for short. A virus is just a program that tells the computer to do something that the
user does not want it to do. It requires a host program to live and infects other files so that it
can “live” longer. A virus can perform destructive actions, such as displaying irritating
messages, overwriting hard drives, or rendering the machine inoperable.
A worm is a program that replicates itself and spreads through network connections to infect
other machines, eating up bandwidth and storage space and slowing computers down. Some
worms use email to send messages to other users, while others use application vulnerabilities
to replicate via the network. The distinction between viruses and worms is beginning to blur,
as many viruses today also use email as their means of propagation.
“Blended threats”, such as Code Red and Nimda, are sophisticated attacks that use multiple
methods and techniques to propagate and inflict damage, thus spreading very rapidly and
causing significant productivity disruptions. Blended threats can be part virus, part worm,
and part backdoor2.
Widely connected enterprise networks and the Internet have enabled viruses, worms and
blended threats to make use of computer networks for propagation, significantly increasing
the speed of infection and damage. The Internet, with its ease of sharing and downloading of
files, has also increased the risk of infection to the average user. A user may infect a computer
by an action as simple as clicking on a downloaded file or an email attachment.
Author: Juniper Networks
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