ARCHIVED: Avoiding computer viruses

Computer viruses implant instructions in other programs or storage devices and can attack, scramble, or erase computer data. The danger of computer viruses lies in their ability to replicate themselves and spread from system to system. Few computing systems are immune to infection.

On this page:

• High-risk behaviors
• How to avoid computer viruses

High-risk behaviors

The following activities are among the most common ways of getting computer viruses. Minimizing the frequency of these activities will reduce your risk of getting a computer virus:

• Freely sharing computer programs and system disks, or downloading files and software through file-sharing applications such as BitTorrent, eDonkey, and KaZaA
  
  
• Clicking links in instant messaging (IM) that have no context or have only general text; for more information, see What should I do if my computer is infected with an instant messaging (IM) Trojan?
  
  
• Downloading executable software from public-access bulletin boards or web sites
  
  
• Using your personal disk space with public computers or other computers that are used by more than one person
  
  
• Opening email attachments from people you don't know or without first scanning them for viruses; for more information, see Using Symantec/Norton AntiVirus Corporate Edition in Windows, how do I immediately scan a file, folder, or drive for viruses? and Using Norton AntiVirus for Mac OS or Mac OS X, how do I immediately scan a file, folder, or drive for viruses?
  
  
• Opening any email attachment that ends in .exe, .vbs, or .lnk on a computer running Microsoft Windows (At Indiana University, UITS blocks certain attachments that commonly harbor viruses from being delivered via email; for more information, see At IU, what types of attachments are blocked from my email account?)
  
  
• Continually running your Windows computer as an administrator; for more information, see In Windows, why should I avoid running my computer as an administrator?

How to avoid computer viruses

Following are some recommendations for safe computing:

• The most important thing you can do to keep your computer safe is to install virus detection software and keep the virus patterns up to date. Antivirus programs perform two general functions: scanning for and removing viruses in files on disks, and monitoring the operation of your computer for virus-like activity (either known actions of specific viruses or general suspicious activity). Most antivirus packages contain routines that can perform each kind of task.

  Note: The University Information Security Office (UISO) recommends that you run the latest version of Symantec/Norton AntiVirus software (available to IU students, faculty, and staff for free via IUware) for your operating system, being sure to upgrade safely (see In Windows, how do I safely upgrade to the latest Symantec Endpoint or AntiVirus software?), and that you update your virus definitions daily and scan your computer weekly. For instructions, see:

  • Windows: In Symantec/Norton AntiVirus for Windows, how do I schedule automatic LiveUpdates and virus scans?
  • Mac OS and OS X: In Norton AntiVirus for Mac OS or Mac OS X, how do I schedule automatic LiveUpdates and virus scans?
  
  
• Keep your operating system current with the latest patches and updates. The writers of viruses and worms often exploit bugs and security holes in operating systems and other computer software. Software manufacturers frequently release patches for such holes. For information on obtaining the latest patches, see For Windows, how can I get software updates and patches? and For Mac OS or Mac OS X, how do I obtain and install system software updates?
  
  
• Back up your files. Viruses are one more very good reason to always back up your files.

  Note: If you back up a file that is already infected with a virus, you can re-infect your system by restoring files from the backup copies. Check your backup files with virus scanning software before using them.

• Keep your original application and system disks locked (write-protected). This will prevent the virus from spreading to your original disks.
  
  
• If you must insert one of your application disks into an unknown computer, lock (write-protect) it first, and unlock your application disk only after verifying that the machine is virus-free.
  
  
• Obtain public-domain software from reputable sources. Check newly downloaded software thoroughly using reputable virus detection software on a locked floppy disk for any signs of infection before you copy it to a hard disk. This can also help protect you from Trojan horse programs.
  
  
• Quarantine infected systems. If you discover that a system is infected with a virus, immediately isolate it from other systems. In other words, disconnect it from any network it is on and don't allow anyone to move files from it to another system. Once the system has been disinfected, you can copy or move files.
  
  
• If you use a desktop version of Outlook, minimize use of the preview or reading pane feature.

Also see:

• What should I do if I receive a computer virus alert message via email?
• In Mac OS and Mac OS X, how can I protect myself from viruses?
• What is Microsoft Word's macro virus protection tool, and how do I activate it?