Top 10 Viruses

Here are the top 10 viruses as of October 2003. It’s not easy keeping up on this sort of thing with the way things change so quickly.

Not all of these viruses above are destructive, however the ones that aren’t make up for it by being very annoying.

Types of Viruses

There are several types of actual viruses. As I mentioned above, Trojan Horses and Worms aren’t actual viruses. Below are several different viruses and a short description of each.

• Macro Viruses: Macro viruses now account for over 80% of all viruses. These viruses are capable of changing, or “mutating”, which makes it more difficult for an anti-virus program to pick it up. E-mail is a favorite domain of macro viruses.
  
• File Viruses: These viruses will spread on your system when the file that is infected is used. They either attach themselves to files to alter their properties, or they rename extensions such as .com and .exe, although they will affect others as well.
  
• Boot Sector Viruses: The boot sector is vital on every floppy disk and hard disk. The boot sector can get a virus if it is used when there is an infected media present, such as booting off of an infected floppy diskette. The hard drive can be infected by this because the virus is loaded into memory from the floppy, and as soon as you access the hard drive it is transferred from memory to the hard drive’s boot sector.

The above viruses can also have variations on them that affect their characteristics. Below are some of the techniques they use.

• Multi-Partite Viruses: These will attack multiple targets, such as your boot disk AND files.
  
• Polymorphic Viruses: These viruses will mutate to escape detection. Boot sector, file, and macro viruses have been found to date like this.
  
• Stealth Viruses: They hide in memory and try to escape detection there. If your anti-virus program doesn’t scan memory, they spread.
  
• Retro Viruses: These are sort of an anti-anti-virus. They hunt down your anti-virus software and try to destroy the definitions, or instructions for it.

Virus Myths

According to Symantec, here are the top 5 myths about viruses. While viruses are capable of damaging systems, they can’t do the following:

1. Viruses don’t infect files on write protected disks.
   
2. Viruses don’t affect compressed files. However, applications within a compressed file could have been infected before they were compressed. Some viruses are known to insert copies of themselves in already-created archives.
   
3. Viruses don’t infect computer hardware such as monitors or computer chips; they only infect software. They can, however, damage certain types of hardware such as flash-memory.
   
4. Macintosh viruses don’t infect DOS-based computer software, and vice versa. For example, the Michelangelo virus does not infect Macintosh applications. Again, an exception to this rule are the Word and Excel macro viruses, which infect spreadsheets, documents, and templates which can be opened by either Windows or Macintosh computers.
   
5. Viruses usually do not identify themselves as viruses, even after they do something destructive.

Are you scared yet? There’s no real reason to be if you use some basic precautions and common sense.

• Use an Anti-Virus Program. There are dozens of them out there, ranging in price from free to thousands of dollars for corporate software. Check out Symantec or McAfee for two of the more popular ones.
  
• I can’t stress this one enough. Don’t open attachments from ANYBODY unless you know exactly what they have sent you and scanned it with your anti-virus software. (What? You don’t have anti-virus software? Didn’t you read the above note???)
  
• Please don’t forward virus warnings that you have received from half of the civilized world, even if you are told they got it from a “reputable” source. 99.9% of the time they are a hoax, and the best thing to do is investigate first before firing off your own warning to everyone. Check out the above-mentioned Symantec or McAfee web sites as they are very up to date on these things. It’s their job.

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