COMPUTER VIRUSES

Computer Viruses

A computer virus is a piece of software that "invades" a computer. As such, a computer virus is one of several kinds of infections, including Trojan horses and worms. Infections are themselves a subset of possible attacks on computers and networks; other attacks include probes, unauthorized access, and denial of service, Internet sniffers, and large-scale scanning. This entry focuses on viruses, worms, and Trojan horses—collectively termed electronics infections—the three most common kinds of attacks and the ones best known by the public (Carnegie Mellon University Internet site). All such infections constitute multiple ethical and political issues: the responsibilities to protect against them, determining consequences for those responsible for attacks, and how to educate users about their vulnerabilities.

Technical Features

A virus is a piece of software that is hidden inside a larger program. When the larger program is executed, the virus is executed as well. During that execution, the virus can try to fulfill its purpose, often to replicate (that is, copy) itself in other programs on its host machine or (via the Internet) to new host machines. This copying and sending takes up resources on the original machine, on the Internet's communications capacity, and on any new machines infected. For a major virus attack, the loss of resources can cost billions of dollars. (Gilman, PP: 998-1000)

One variation on the more traditional application-borne computer virus is the e-mail virus. An e-mail virus attaches itself to a piece of e-mail instead of to a program. Another subspecies of computer virus is the "logic bomb." A logic bomb is a virus because it resides inside the operating system or an application; the variation is that a logic bomb executes its harmful side effect only when certain conditions are met, typically when the system clock reaches a particular date. At the appointed time, the virus can do something relatively harmless, like flashing a provocative text message on the screen; but it could also do something far more serious, such as erasing significant portions of the resident host's hard drive.

A virus requires a program or e-mail to hide in. But a computer worm works independently. A computer worm uses computer networks and security flaws to replicate itself on different networked computers. Each copy of the worm scans the network for an opening on another machine and tries to make a new copy on that machine. As this process is repeated over many generations, the computer worm spreads. As with viruses, both the propagation and any other side effects can be frivolous or draconian.

A Trojan horse is a complete computer program that masquerades as something different. For example, a web site might advertise a freeware computer game called Y. But when someone downloads and runs a copy of Y, Y erases the hard drive of the host machine. Unlike viruses, a Trojan horse does not include a self-replication mechanism inside its program. (Miller, PP: 398-401)

Ethical Issues

Early in the history of computer development, some people thought of electronic infections as relatively harmless, high-tech pranks. But once these ...