Confessions of an Internet hacker: Stealing your personal information was hard to resist

California CPA, March, 2002 by Larry Russell

Virus Types

Viruses fall into four main classes:

Macro Viruses

According to the International Computer Security Association, 80 percent of viruses are macro viruses--and the numbers are growing. These are not specific to an operating system and spread with ease via e-mail attachments, floppy disks, Web downloads, file transfers and general use applications.

Macro viruses are application-specific. They infect macro utilities within Microsoft Word and Excel, and can infect hundreds of files if undeterred. They can infect at different points in a file's use, such as when it is opened, saved, closed or deleted.

Trojans

Trojan viruses hide themselves and quietly open a communication port on your Internet-connected PC. You may have installed a personal firewall or be inside a secured network, but this virus type opens back doors so that hackers can access your machine to steal data or use it as a zombie to attack other network PCs. These trojans are distributed by e-mail or picked up at unseemly Web sites referred to as Web bombs.

File Infecting Viruses

File infectors are parasitic viruses that operate in memory. They usually infect executable files with these extensions: *.COM, *.EXE, *.DRV, *.DLL, *.BIN, *.OVL and *.SYS. They activate every time the infected file is executed by copying themselves into other executable files and then remain in memory. The vast majority operate in a DOS 16-bit environment. Although some have successfully infected Microsoft Windows.

Boot Sector Viruses

This virus type was the most prevalent until the mid-1990s, spreading primarily in the 16-bit DOS world via floppy diskettes. It infects the boot sector on a floppy disk and spreads to a user's hard drive and can infect the master boot record (MBR) on a hard drive. Once the MBR or boot sector on a drive is infected, the virus infects the boot sector of floppies accessed on that computer.

How to Protect Against Viruses

The following steps will help protect users against most viruses:

* Install on every computer an industry standard virus protection, such as Norton AntiVirus, McAfee AntiVirus or Tend PC-cilin.

* Install server-based anti-virus protection on both file and e-mail servers.

* Turn on all the virus protection features such as scanning executing applications and opening data files.

* Enable Web filters, heuristics and today's most important option--POP3 or e-mail security.

* Stay current on the software virus application engine and update virus definition files at least once a week. New viruses strike within hours of their introduction to the Internet. A good virus software company will have the antidote within hours of a new virus introduction.

* Scan your hard drives regularly--at least once per week. Some viruses will hide themselves in a downloaded file and are set not to trigger until a future date. Regular virus scans will find and deactivate these sleepers.

* Save all e-mail attachment files and scan them before opening.

Most viruses are sent from people you know. You were in their e-mail address book and the virus selected you as its next victim.