Hardware Reference
In-Depth Information
are discovered, the company updates the virus-defi nition fi le for its antivirus program and
downloads it to users as an update. Having the most up-to-date defi nitions is critical for
effective virus protection, so you must regularly update your antivirus software (or better
yet, set it to update itself automatically).
In addition, many antivirus programs create an MD5 for each application.
MD5
stands
for
Message Digest Version 5
, a math calculation that results in a unique value used to
refl ect the data being checked. If the MD5 changes, this may be treated as a virus attack.
Antivirus applications are normally
resident
, meaning they're continuously running
in the background, analyzing your system and any programs when they're opened/closed
as well as any fi les that are opened/closed. Some antivirus programs check incoming and
outgoing email too, as well as web pages you visit. You can also tell your antivirus program
to do a complete scan of all your fi les any time you like. (It will probably offer to do one
right after you install the antivirus software.)
When your antivirus program fi nds something suspicious, a message appears, giving you
the choice of deleting or quarantining the infected fi le(s). Deleting a fi le removes it from
your system. Quarantining it places it in an off-limits area so it can't be run, but keeps it
on your system. You might quarantine a fi le that you wanted to share with an IT professional
who was tracking virus infections on your network, for example.
EXERCISE 9.10
Install and Use an Antivirus Application
1.
If you don't already have an antivirus application, download and install one. For Windows
systems, Microsoft's Home Security Essentials program is free, and it will work well for
this exercise. You can download it at
www.microsoft.com/en-us/security_essentials/
default.aspx
. Or, if you already have an antivirus application, open it.
2.
Using whatever antivirus software you have installed, do the following:
a.
Update the virus defi nitions.
b.
Run a complete system scan.
3.
If any viruses are found, quarantine or delete the fi les that contain them.
Antispyware Software
Antispyware applications look for known spyware and adware programs and offer to disable
them or remove them from your system. Like antivirus applications, antispyware programs
look for defi nitions—that is, code snippets that identify a spyware or adware component.
Most antispyware applications also can remove lesser security and privacy threats, such as
tracking cookies. Many antivirus applications include antispyware protection too, so you may
not have to bother with a separate antispyware application.
Some antispyware applications run all the time in the background, like an antivirus
application. Others run only when you specifi cally open them and initiate a scan.
