Virus

VIRUS

TYPE OF VIRUSES

Virus Type
A virus is a program that has two functions: proliferate (make more copies of itself) and activate (at some signal count, date, and so on, do something-usually something bad like delete the boot sector). A virus does not have to do damage to be a virus.

Boot Sector
Boot sector viruses change the code in the master boot record (MBR) of the hard drive.

Executable
Executable viruses reside in executable files. They are literally extensions of executables and are unable to exist by themselves.

Macro
Macro viruses are specially written application macros. These viruses will auto-start when the particular application is run and will then attempt to make more copies of them-selves.

Trojan
Trojans are true, freestanding programs that do something other than what the person who runs the program thinks they will do. An example of a Trojan would be a program that a person thinks is a game but that is actually a CMO eraser. Some Trojans are quite sophisticated. It might be a game that works perfectly well, but when the user quits the game, it causes some type of damage.

Worm
A worm is a very special form of virus. Unlike all of the other viruses described, a worm does not infect other files on the computer. Instead, a worm replicates by making copies of itself on other systems on a network by taking advantage of security weaknesses in networking protocols.

Bimodal/Bipartite
A bimodal or bipartite virus uses both boot-sector and executable functions.

Antivirus Tools
The only way to protect your PC permanently from getting a virus is to disconnect from the Internet and never permit any potentially infected software to touch your precious computer. Because neither scenario is likely these days, you need to use a specialized antivirus program to help stave off the inevitable virus assaults.

Polymorphics/Polymorphs
A polymorphs virus attempts to change its signature to prevent detection by antivirus programs, usually by continually scrambling a bit of useless code.

Stealth
The term “stealth” is more of a concept than an actual virus function. Most stealth virus programs are boot sector viruses that use various methods to hide from antivirus software.

Virus Prevention Tips
The secret to preventing damage from a virus attack is to keep from getting one in the first place. As discussed earlier, all good antivirus programs include a virus shield that will automatically scan floppies, downloads, and so on. Use it. It is also a good idea to scan a PC daily for possible virus attacks. Again, all antivirus programs include TSRs that will run every time the PC is booted. Last but not least, know where software has come from before you load it. Although the chance of commercial, shrink-wrapped software having a virus is virtually nil (a couple of well-publicized exceptions have occurred), that illegal copy of “Unreal Tournament” you borrowed from a local hacker should definitely be inspected with care.
Get into the habit of having an antivirus floppy disk-a bootable, copy-protected floppy with a copy of an antivirus program. If you suspect a virus, use the diskette, even if your antivirus program claims to have eliminated it. Turn off the PC and reboot it from the antivirus diskette. Run your antivirus program’s most comprehensive virus scan. Then check all removable media that were exposed to the system and any other machine that may have received data from, or is networked to, the cleaned machine. A virus can often go for months before anyone knows of its presence.

General System Sluggishness
Every PC gets slower and stodgier overtime. You load and unload programs, you download stuff off the Internet, the system crashes and scatters temp files all over the place-all of these factors contribute to the decline of snappiness. Sometimes the decline comes in a more dramatic fashion, though. A client of mine recently bought a new Pentium 4 system with all the bells and whistles.