CertiGuide to Network+  9  Chapter 1000:  Security in the Real World

RAS (Remote Access Service) 1 2 Pop Quiz 1000.01

In addition to misuse of RAS connections, another way client security can be compromised is through a computer virus. A virus is a program that infects a computer and makes a copy of its own self to pass on much like a virus in the organic world. Generally, the designer goes to great lengths to hide the virus so it may reproduce without detection. A virus can hide in either a program (.com, .exe) or in a macro language, such as with Word or Excel macros. The Melissa virus is a classic example of macro virus.

Viruses do not have to become apparent at the moment of infection. Frequently they will hide so they may be spread without detection. The trigger to launch the virus can be X number of boots, a specific date or other trigger.

Generally speaking there are three types of viruses. They are:

• Non-destructive:. These entries represent no serious threat, and generally exhibit themselves as messages on the screen, usually political.
  
  
• Nuisance: These are more annoying then non-destructive. They may demonstrate themselves by odd behavior, such as locking up certain programs. After you re-boot, everything is fine until another ‘magic’ point.
  
  
• Destructive: These are the nastiest viruses. Typical of these types of viruses is to infect the boot sector destroying the allocation table that causes total data loss.

RAS (Remote Access Service) 1 2 Pop Quiz 1000.01