ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

Computer VirusAuthorization and intrusion. Software programs allow ahierarchy of approvals to be established for access to data.In a company, for example, senior managers can be authorizedto view and even manipulate data that morejunior personnel do not have access to. Other programsact as guardians of the data, and detect any unauthorizedor unusual actions on the computer (i.e., hacking).Computers connected to the Internet are oftenequipped with software known as a firewall. The firewallfunctions to monitor incoming transmissions and to restrictthose that are deemed suspicious. It is a controlledgateway that limits who and what can pass through. Anumber of vendors offer firewall programs. Like anti-virussoftware, these programs can and should be frequentlyupdated, since those who seek to maliciously gain remoteaccess to computers are constantly developing methodsto thwart the firewall barrier.❚ FURTHER READING:BOOKS:Bentley, Tom, and Jon Hastings. Safe Computing: How toProtect Your Computer, Your Body, Your Data, YourMoney and Your Privacy in the Information Age. Concord,CA: Untechnical Press, 2000.Bishop, Matt. Computer Security: Art and Science. Boston:Addison Wesley Professional, 2002.Cheswick, William R., Steven M. Bellovin, and Aviel D.Rubin. Firewalls and Internet Security: Repelling theWiley Attacker, Second Edition. Boston: Addison WesleyProfessional, 2003.Stoll, Clifford. Cuckoo’s Egg: Tracking a Spy through theMaze of Computer Espionage. New York: Simon andSchuster, 2000.Whittaker, James A., and Herbert Thompson.How to BreakSoftware Security: Art and Science. Boston: AddisonWesley Professional, 2002.SEE ALSOComputer Hardware SecurityComputer VirusCyber Security❚ LARRY GILMANComputer VirusA computer virus is a program or segment of executablecomputer code that is designed to reproduce itself incomputer memory and, sometimes, to damage data.Viruses are generally short programs; they may eitherstand-alone or be embedded in larger bodies of code. TheEncyclopedia of Espionage, Intelligence, and SecurityA computer screen e-mail inbox showing subject names reading‘‘ILOVEYOU,’’ that contains a powerful computer virus that struck globalcommunications systems and crippled government and corporate computernetworks around the world in May, 2000. AP/WIDE WORLD PHOTOS.term “virus” is applied to such code by analogy to biologicalviruses, microorganisms that force larger cells to manufacturenew virus particles by inserting copies of their owngenetic code into the larger cell’s DNA. Because DNA canbe viewed as a data-storage mechanism, the parallel betweenbiological and computer viruses is remarkably exact.Many viruses exploit computer networks to spreadfrom computer to computer to computer, sending themselveseither as e-mail messages over the Internet ordirectly over high-speed data links. Programs that spreadcopies of themselves over network connections of anykind are termed “worms,” to distinguish them from programsthat actively copy themselves only within the memoryresources of a single computer. Some experts havesought to restrict the term “virus” to self-replicating codestructures that embed themselves in larger programs andare executed only when a user runs the host program, andto restrict the term “worm” to stand-alone code thatexploits network connections to spread (as opposed to,say, floppy disks or CD ROMs, which might spread avirus). However, virus terminology has shifted over thelast decade, as computers that do not communicate overnetworks have become rare. So many worm/virus hybridshave appeared that any distinction between them is rapidlydisappearing. In practice, any software that replicatesitself may be termed a “virus,” and most viruses are263