Malicious Mobile Code

Signs and Symptoms of Windows NT Virus Infections

How a computer virus presents itself is dependent on the type of virus and the Windows platform infected. Typically, the older and more widespread the virus, the less likely it will be able to spread and cause harm. In this section, we will cover the signs and symptoms of computer virus infection in Windows.

Common Signs and Symptoms

Some signs of virus infection are:

• The normal signs and symptoms of successful computer virus infection apply. Hacker-sounding taunts, such as “Gotcha” or “You’re infected,” should be a major clue. Randomly appearing graphics, sounds, file disappearance -- all of these should be taken as possible signs of virus infection.

• Sudden, unexpected executable file growth and/or date changes. This is one of the quickest ways of spotting a computer virus, but you have to know what to look for. Windows will frequently update executables (i.e., EXEs, DLLs) as a normal part of business. The trick is to look for widespread executable updates at the same time as other suspicious symptoms started occurring.

• Unexpected modification of startup areas (AUTOEXEC.BAT) registry, Startup group.

• Sudden slowness with file execution might be a sign.

• Sudden, unexpected long-term hard drive accessing after your program or data is loaded could be suspect.

Programs Won’t Start

Windows 16-bit and 32-bit program files infected with a DOS virus will usually fail to run. DOS viruses infecting newer versions of COMMAND.COM may result in ...