Page 1457 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

in 2016 and this trend only continues, with some sources suggesting
that 200,000 new malware variants appear on the internet every day!

Hundreds of thousands of variations of these viruses strike
unsuspecting computer users each day. Many carry malicious payloads
that cause damage ranging in scope from displaying a profane message
on the screen all the way to causing complete destruction of all data
stored on the local hard drive.

As with biological viruses, computer viruses have two main functions

—propagation and destruction. Miscreants who create viruses
carefully design code to implement these functions in new and
innovative methods that they hope escape detection and bypass
increasingly sophisticated antivirus technology. It’s fair to say that an
arms race has developed between virus writers and antivirus
technicians, each hoping to develop technology one step ahead of the
other. The propagation function defines how the virus will spread from
system to system, infecting each machine it leaves in its wake. A virus’s

payload delivers the destructive power by implementing whatever
malicious activity the virus writer had in mind. This could be anything
that negatively impacts the confidentiality, integrity, or availability of
systems or data.

Virus Propagation Techniques

By definition, a virus must contain technology that enables it to spread
from system to system, aided by unsuspecting computer users seeking

to share data by exchanging disks, sharing networked resources,
sending electronic mail, or using some other means. Once they’ve
“touched” a new system, they use one of several propagation
techniques to infect the new victim and expand their reach. In this
section, we’ll look at four common propagation techniques: master
boot record infection, file infection, macro infection, and service

injection.

Master Boot Record Viruses The master boot record (MBR) virus
is one of the earliest known forms of virus infection. These viruses
attack the MBR—the portion of bootable media (such as a hard disk,
Universal Serial Bus (USB), or compact disc/digital versatile disc
(CD/DVD)) that the computer uses to load the operating system