Ch. 3: Internet Issues

Viruses

In the 1980s microcomputer programs called rogue software began to appear that would secretly hide themselves within a user's program (e.g., a game). When a user ran the program (e.g., played the game), the hidden program would "infect" other programs on the user's computer by secretly copying itself into them. Since these hidden programs mimic the spread of biological viruses, they were dubbed computer viruses. Some computer viruses are benign, but others behave maliciously, most often by erasing or destroying data. One virus alone (the "Love Bug" of 2000) was estimated to have cost businesses $2.6 billion worldwide.

Most viruses were limited to personal computers (PCs), whose operating systems contained no memory-protection mechanisms to prevent a program from altering other programs. Early viruses thus spread from PC to PC as people used floppy disks containing infected files on different computers. As computer networks became more common, they provided new ways for viruses to spread.

As computer networks, e-mail, and the Internet became increasingly popular, programs containing viruses could be downloaded or sent as e-mail attachments, making it even easier for viruses to spread. However, the program containing a virus must be run in order for the virus to spread. Various companies sell virus-protection software, including a program called a virus scanner that can be used to scan a program, determine whether it contains a virus, and remove the virus if necessary. To avoid being infected, you should always use a virus scanner to scan disks and/or programs received from someone else before you use them.

In the mid-1990s, Microsoft added to its office suite software a feature that allows users to record a sequence of commands and store this sequence within a document. Such command sequences are called macros. When malicious individuals discovered that a macro can be set to run automatically when the document containing it is opened, a whole new class of viruses appeared called macro viruses. Macro viruses can be just as destructive as traditional viruses and can be hidden within Microsoft Office documents received as e-mail attachments. To avoid being vulnerable to such viruses, users should make sure they have anti-virus software running before opening e-mail attachments. Also, they should continue to install the latest updates available for both their Microsoft products and anti-virus software.

Another category of assaults upon a network are denial-of-service (DoS) attacks. In this case, the software is designed to engineer the flooding of a network with useless traffic, thereby rendering it unable to operate.

An agency called the Computer Emergency Response Team (CERT) has the responsibility of monitoring Internet activities, serving as a central site where information about computer security problems can be reported and disseminated. It is also responsible for dealing with Internet-related crises as they arise.

Symantec Corporation also maintains a comprehensive website dedicated to computer viruses.

Grisoft Corporation makes available an excellent and free anti-virus program called AVG.

If you encounter technical errors, contact computing@calvin.edu.