Encyclopedia of Computer Science and Technology

100 computer crime and securitycomputer crime and securityThe growing economic value of information, products, andservices accessible through computer systems has attractedincreased attention from opportunistic criminals. In particular,the many potential vulnerabilities of online systemsand the Internet have made computer crime attractive andpose significant challenges to professionals whose task it isto secure such systems.The motivations of persons who use computer systemsin unauthorized ways vary. Some hackers primarily seekdetailed knowledge of systems, while others (often teenagers)seek “bragging rights.” Other intruders have the moretraditional criminal motive of gaining access to informationsuch as credit card numbers and personal identities thatcan be used to make unauthorized purchases (see identitytheft). Computer access can also be used to intimidate (seecyberstalking and harassment), as well as for extortion,espionage, sabotage, or terrorism (see cyberterrorism).Attacking and defending information infrastructure is nowa vital part of military and homeland security planning (seeinformation warfare).According to the federal Internet Crime Complaint Center,in 2006 the most commonly reported computer-relatedcrime was auction-related fraud (44.9 percent), followed bynondelivery of goods (19 percent)—these no doubt reflectthe high volume of auction and e-commerce transactions.Various forms of financial fraud (including identity theft)make up most of the rest.The new emphasis on the terrorist threat following September11, 2001, has included some additional attention tocyberterrorism, or the attack on computers controlling keyinfrastructure (including banks, water and power systems,air traffic control, and so on). So far ideologically inspiredattacks on computer systems have mainly amounted tosimple electronic vandalism of Web sites. Internal systemsbelonging to federal agencies and the military tend to berelatively protected and isolated from direct contact withthe Internet. However, the possibility of a crippling attackor electronic hijacking cannot be ruled out. Commercialsystems may be more vulnerable to denial-of-service attacks(see below) that cause economic losses by preventing consumersfrom accessing services.Forms of AttackSurveillance-based attacks involve scanning Internet trafficfor purposes of espionage or obtaining valuable information.Not only businesses but also the growing number ofInternet users with “always-on” Internet connections (seebroadband) are vulnerable to “packet-sniffing” softwarethat exploits vulnerabilities in the networking software oroperating system. The main line of defense against suchattacks is the software or hardware firewall, which both“hides” the addresses of the main computer or network andidentifies and blocks packets associated with the commonforms of attack (see firewall).In the realm of harassment or sabotage, a “denial of service”(DOS) attack can flood the target system with packetsthat request acknowledgment (an essential feature of networkoperation). This can tie up the system so that a Webserver, for example, can no longer respond to user requests,making the page inaccessible. More sophisticated DOSattacks can be launched by first using viruses to insert programsin a number of computers (a so-called botnet), andthen instructing the programs to simultaneously launchattacks from a variety of locations.Computer viruses can also be used to randomly vandalizecomputers, impeding operation or destroying data (seecomputer virus). But a virus can also be surreptitiouslyinserted as a “Trojan horse” into a computer’s operating systemwhere it can intercept passwords and other information,sending them to the person who planted the virus. Viruseswere originally spread through infected floppy disks (often“bootleg” copies of software). Today, however, the Internetis the main route of access, with viruses embedded in e-mailattachments. This is possible because many e-mail and otherprograms have the ability to execute programs (scripts) thatthey receive. The main defense against viruses is regularuse of antivirus software, turning off scripting capabilitiesunless absolutely necessary, and making a policy of notopening unknown or suspicious-looking e-mail attachmentsas well as messages that pretend to be from reputable banksor other agencies (see phishing and spoofing).Computer SecurityBecause there are a variety of vulnerabilities of computersystems and of corresponding types of attacks, computersecurity is a multifaceted discipline. The vulnerability ofcomputer systems is not solely technical in nature. Sometimesthe weakest link in a system is the human link.Hackers are often adept at a technique they call “socialengineering.” This involves tricking computer operatorsinto giving out sensitive information (such as passwords)by masquerading as a colleague or someone else who mighthave a legitimate need for the information.Since computer crimes and attacks can take so manyforms, the best defense is layered or in depth. It includesappropriate software (firewalls and antivirus programs,and network monitoring programs for larger installations).It emphasizes proper training of personnel, ranging fromsecurity investigators to clerical users. Finally, if informationis compromised, the use of strong encryption can makeit much less likely to be usable (see encryption).While the flexibility and speed of the Internet can aidattackers, it can also facilitate defense. Emergency responsenetworks and major vendors of antivirus software canquickly disseminate protective code or “patches” that closevulnerabilities in operating systems or applications.The growing concern about vulnerability to computerintrusion and information theft has also been reflected inattempts to make operating systems inherently more secure.The introduction of new security features in Microsoft WindowsVista has received mixed reviews. Some features, suchas User Account Control, make it harder for viruses orother automated attacks to access critical system resources,but also annoy users by constant requests for permission tocarry out common tasks. This reflects a fundamental truth:Security features that make everyday computing moretedious tend to be turned off or bypassed by users.