Computer viruses are programs that spread or self-replicate. The virus may arrive in an  e-mail message as an attachment or be activated by visiting a malicious web site. Some viruses consume storage space or simply cause unusual screen displays. Others destroy information. If a virus infects your PC, all the information on your hard drive may be lost and/or compromised.  Also, a virus in your PC may easily spread to other machines that share the information you access.  (State of New Jersey, 2008)

By Any Other Name:

Although they may be introduced into your system by the same means, not all computer viruses behave the same way.  Some of the most common types of computer viruses include:

  • Trojan Horse: A Trojan horse program has the appearance of having a useful and desired function. While it may advertise its activity after launching, this information is not apparent to the user beforehand. Secretly the program performs other, undesired functions. A Trojan Horse neither replicates nor copies itself, but causes damage or compromises the security of the computer.
  • Worms: A worm is a program that makes and facilitates the distribution of copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism.
  • Bootsector Virus: A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup.
  • Macro Virus: Macro viruses are viruses that use another application’s macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents.
  • Memory Resident Viruses: Memory Resident Viruses reside in a computers volitale memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after its initiating program closes.
  • Rootkit Virus: A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by trojans and are normally disguised as operating system files.
  • Logic Bombs/Time Bombs: These are viruses which are programmed to initiate at a specific date or when a specific event occurs. Some examples are a virus which deletes your photos on Halloween, or a virus which deletes a database table if a certain employee gets fired.  (Top Choice Previews)

 A Growing Problem:

There were  1 ,017,208 viruses reported during the first of 2010 alone. This represent(ed) an increase of 50 percent compared to (the previous) year. Experts (predicted) a  record total of over two million new malware programs for 2010 as a whole.  (Leeuwen, 2010) With statistics like this indicating an ever-increasing threat of attacks, it’s important to know what to look out for.   Signs that your computer is  infected by a virus may include:

  • Your computer behaves strangely, i.e. in a way that you haven’t seen before. 
  • You see unexpected messages or images. You hear unexpected sounds, played at random.
  • Programs start unexpectedly. Your personal firewall tells you that an application has tried to connect to the Internet (and it’s not a program that you ran).
  • Your friends tell you that they have received e-mail messages from your address and you haven’t sent them anything.
  • Your computer ‘freezes’ frequently, or programs start running slowly.
  • You get lots of system error messages. The operating system will not load when you start your computer.
  • You notice that files or folders have been deleted or changed. You notice hard disk access (shown by one of the small flashing lights) when you’re not aware of any programs running.
  • Your web browser behaves erratically, e.g. you can’t close a browser window. (Kaspersky Lab)

If you feel your computer may have been infected by a virus, please contact the SJU Technology Service Center (TSC) at x2920 or by email at Remember: The TSC will NEVER ask you for your password or Social Security number.


State of New Jersey. 2008. New Jersey Info Secure. State of New Jersey. [Online] 2008.

Kaspersky Lab. Symptoms. Kaspersky Lab. [Online]

Leeuwen, Danielle Van. 2010. News Details. G Data. [Online] 2010.

Top Choice Previews. Antivirus Software. Top Choice Previews. [Online]