Oregon State University

Computer Viruses

What is a computer virus?

A computer virus or malware is a commonly used term to describe all types of malicious software including Trojans, worms, adware, and spyware. Each have slightly different functions, but usually either try and damage the software on your computer, or send information about your computer usage to an outside source over the internet. The details of each type are explained below:

Types of computer viruses

Trojans: A Trojan, as the name suggests, pretends to be something good, like virus scanning software or other useful applications. In reality they run malicious programs in the background that can perform any number of functions, like allowing an outside user to copy your files, see your browsing history, or even take remote control of your computer.

Worms: A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other computers on the network, and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or devour files on a targeted computer.

Adware: Adware or advertising-supported software is any software package which automatically plays, displays, or downloads advertisements to a computer after the software is installed on it or while the application is being used. Adware is usually seen by the developer as a way to recover development costs, and in some cases it may allow the software to be provided to the user free of charge or at a reduced price. As a result, the advertisements may be seen by the user as interruptions, annoyances or as distractions from the task at hand.

Spyware: Spyware is computer software that is unknowingly installed on a personal computer to collect information about a user, their computer or browsing habits without the user's informed consent. Spyware programs can collect various types of personal information, such as Internet surfing habits and sites that have been visited, but can also interfere with user control of the computer in other ways, such as installing additional software and redirecting Web browser activity. Spyware is known to change computer settings, resulting in slow connection speeds, different home pages, and/or loss of Internet or functionality of other programs.

How can my computer become infected?

Unfortunately, there are many ways your computer can become infected. Some of the main causes to an infected computer included: illegally downloading music and movies, clicking on ads, browsing to compromised websites, and in general not being cautious when it comes to web browsing. Be sure to follow the safe browsing habits and remember, it's always better to be safe then to be sorry.

What are the symptoms of a virus?

There is a wide variety of virus symptoms that differ based on what type of infection you have and how far the virus has progressed. A list of common symptoms is listed below:

  • Speed decrease
  • Unexplained freezing/crashing
  • Programs that won’t launch
  • New programs won’t install
  • Computer has trouble booting windows
  • Internet access is blocked (completely or certain sites)
  • Desktop/appearance/screen saver and other visual settings are changed unexpectedly
  • Unable to open files or folders
  • Files or folders are deleted unexpectedly
  • False pop-ups that appear warning you about viruses
  • Deteriorating condition over a period of a few days to a few weeks (viruses that download more malicious software as time goes on)
  • Unable to print documents
  • Your hard disk runs out of free space (this comes from an infected file making copies of itself)

How can I protect myself?

  • For a personally owned computer, use ClamXAV and Windows Defender/Security Essentials. For instructions on installing and basic use of these products please go here. If your computer is university owned, please talk to your computer support group for assistance.
  • Keep your computer's operating system up to date using Windows Update or Software Update on Mac.
  • Read "How to recognize a Fake Virus Alert Message."
  • NEVER use file sharing programs to download games, music, movies, TV shows, etc. A large majority of the files shared on this network are infected.
  • NEVER click advertisements on the Internet.
  • NEVER give anyone your password.
  • NEVER respond to SPAM.
  • READ all warnings very carefully.
  • EDUCATE yourself, your friends and family about infections.
  • NEVER click OK or cancel to warnings like this:

How can I scan and remove a virus infection?

The first order of business is to get anti-virus software. Students and faculty can download ClamXAV and Windows Defender/Security Essentials for free, but the protection shouldn't stop there. We also recommend downloading other virus scanning tools, here at the OSU Computer Helpdesk we often use Malwarebytes and SUPERAntiSpyware both of which are available for free.

Click HERE to watch a tutorial about running a virus scan with Malwarebytes.

After obtaining the software simply run the program and have it scan for viruses. A good habit to exercise before each scan is to double check that the software's definitions are up-to-date. In order to update the definitions there should be either a tab or button that relates to updating the software, e.g. "Check for Updates online."

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