A virus is a program designed to infect and potentially damage files on a computer that receives it. The code for a virus is hidden within a file or program—such as a text document or a spreadsheet program—and when the file is opened or the program is launched, the virus inserts copies of itself, infecting the computer on which these files are opened. Because of this ability to reproduce itself, a virus can quickly spread to other programs, including the computer’s operating system. A virus may reside on a computer system for some time before taking any action detectable to the user. Other viruses may cause trouble immediately. Some viruses cause little or no damage. For example, a virus may manifest itself as nothing more than a message that appears on the screen at certain intervals. Other viruses are much more destructive and can result in lost or corrupted files and data.
Viruses may render a computer unusable, necessitating the reinstallation of the operating system and applications. Viruses can even be written to imbed some small miscalculation into, for example, a spreadsheet program.
This sort of hidden problem may jeopardize the accuracy of all the work done with the infected program for a long time before it is even detected.
Viruses are written to target program files and macros, or a computer’s boot sector, which is the portion of the hard drive that executes the steps necessary to start the hardware and software. Program viruses attach themselves to the executable files associated with software programs, and can then attack any file that is used to launch an application, usually files ending with the “exe” or “com” extensions. Macro viruses infect program templates that are used to create documents or spreadsheets. Once infected, every document or spreadsheet opened with the infected program becomes corrupted. Boot sector viruses attack the computer’s hard drive and launch themselves each time the user boots, or starts, the computer. Viruses are often classified as Trojan Horses or Worms. A Trojan Horse virus is one that appears harmless on the surface but, in reality, destroys files or programs. A Worm attacks the computer’s operating system and replicates itself again and again, until the system eventually crashes.
Another line of viruses is referred to as Malware, or, more generically as Spyware. These are viruses that are imbedded in files downloaded onto an unsuspecting computer while the user is browsing the Internet. Spyware programs, once on a computer, allow the creator of the virus to snoop on or monitor the infected computer’s browser activities. A spyware virus usually implants “pop-up” ads that will appear on a user’s screen periodically. These programs can down a computer, cause it to crash, and in some cases can even record for the sender the recipient’s credit card numbers if it is used to purchase items while online. Spyware is usually a nuisance-level virus but in some cases can pose a more serious threat.
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Viruses And The Internet
The Internet, with its global reach and rapid delivery times, provides the ideal breeding ground for viruses.
Typically, someone who wants to spread a virus does so by sending out an e-mail message containing an infected attachment. The subject line on such a message sounds innocuous, so unsuspecting recipients open the message, unwittingly infecting their computers. More insidious yet, many viruses infect the recipient and then launch e-mail messages using the recipient’s e-mail system address book and send themselves out to all of the recipient’s list of colleagues, clients, vendors, friends, and family for whom an e-mail is found.
With new computer viruses appearing daily, keeping a computer or network of computers free of viruses is a daunting task. If, however, one views the proper use and maintenance of anti-virus software as a necessary part of running computers, the task becomes just another in the list of things one must do to maintain computers. The following are steps every computer user should follow to protect his or her computer from viruses.
1. Install an anti-virus software program to identify and remove viruses before they can cause any damage.
These programs scan, or review, files that may come from floppy diskettes, the Internet, e-mail attachments, or networks, looking for patterns of code that match patterns in the anti-virus software vendor’s database of known viruses. Once detected, the software isolates and removes the virus before it can be activated.
2. Update the anti-virus software weekly. Because the number of viruses is increasing all the time, it is important to keep anti-virus software up-to-date with information on newly identified viruses. Antivirus software vendors are constantly updating their databases of information on viruses and making this information available to their customers via their Web sites or by e-mail.
3. Maintain a regular back-up procedure for all computers. This procedure may be as simple as keeping copies of important files on diskettes or CD-ROMs (in which case original software should be kept with these diskettes or CDs) and it may be as elaborate as a system designed to produce a mirror copy of a system, updating this copy every few minutes. For a small business, the most prudent level of back-up probably falls somewhere between these two extremes. Whatever the schedule is, it should include regular and periodic backing up of all computer systems and the remote storage of the backups’ media in case of fire, flood, etc.
4. Do not open e-mail from unknown recipients or messages that contain unexpected attachments. A user should delete these types of messages. As a general rule, a user should scan every e-mail attachment for viruses before opening it—even an expected attachment—as the sender may have unknowingly sent an infected file.
One of the most costly and memorable viruses was the Love Bug virus of 2000. This virus targeted users of Microsoft’s Outlook e-mail program. Originating in the Philippines, the subject line on the Love Bug message was the inviting “ILOVEYOU.” If a user opened the attachment to this message, the virus quickly began to destroy files, targeting digital pictures and music files. The Love Bug virus also perpetuated itself by forwarding the original message to all e-mail addresses listed in the current recipient’s Outlook address book. In this way, the virus was able to circle the globe in just two hours. The virus brought businesses to a standstill as companies, large and small, were forced to shut off incoming Internet e-mail messages and repair infected systems. In all, the Love Bug virus is estimated to have cost up to $10 billion in lost work hours.
Another record-setting virus, the fastest spreading e-mail worm ever, is MyDoom. This ominously named virus is a computer worm affecting Microsoft Windows.
It was first sighted on January 2004 and was designed to send junk e-mail through infected computers. Early speculation about MyDoom held that the sole purpose of the worm was to perpetrate a distributed “denial-of-service attack” against the SCO Group. A denial of service attack is one in which a company Web site is flooded with e-mail causing it to overload, or shut down, and damaging any sales generated through the site, or services provided on the site.
Most viruses do not reach the level of fame that these two achieved, either because they are programmed to change as they spread, making them harder to identify and stop, or because they attack a niche sector of the computer-using market. Nonetheless, the damage that such viruses, even seemingly innocuous ones, can have on a company are great. Lost computer processing power equals slower-functioning computers, a lost of time and productivity. Lost files take time to retrieve from backup systems, assuming good backups exist. And rebuilding a computer that has been damaged by a virus is timeconsuming for both the technician and the user.
Protection is the best way to save time, money, and the wear and tear that computer problems can have on all the people involved.
See also: Internet Security