Page 1460 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

applications didn’t provide any defense against them. Macro viruses
quickly became more and more commonplace, and vendors rushed to

modify their antivirus platforms to scan application documents for
malicious macros. In 1999, the Melissa virus spread through the use of
a Word document that exploited a security vulnerability in Microsoft
Outlook to replicate. The infamous I Love You virus quickly followed
on its heels, exploiting similar vulnerabilities in early 2000, showing
us that fast-spreading viruses have plagued us for nearly 20 years.

Macro viruses proliferate because of the ease of writing

code in the scripting languages (such as VBA) utilized by modern
productivity applications.

After a rash of macro viruses in the late part of the twentieth century,
productivity software developers made important changes to the
macro development environment, restricting the ability of untrusted
macros to run without explicit user permission. This resulted in a

drastic reduction in the prevalence of macro viruses.

Service Injection Viruses Recent outbreaks of malicious code use
yet another technique to infect systems and escape detection—
injecting themselves into trusted runtime processes of the operating
system, such as svchost.exe, winlogin.exe, and explorer.exe. By
successfully compromising these trusted processes, the malicious code
is able to bypass detection by any antivirus software running on the

host. One of the best techniques to protect systems against service
injection is to ensure that all software allowing the viewing of web
content (browsers, media players, helper applications) receives
current security patches.

Platforms Vulnerable to Viruses

Just as most macro viruses infect systems running the popular
Microsoft Office suite of applications, most computer viruses are

designed to disrupt activity on systems running versions of the world’s
most popular operating system—Microsoft Windows. In a 2017
analysis by av-test.org, researchers estimated that 77 percent of