This is a prepublication version of a paper that appeared in Global Dialogue, Autumn, 2000.
In 1996, a computer hacker allegedly associated with the White Supremacist movement temporarily disabled a Massachusetts
Internet Service Provider and damaged part of the ISP=s record keeping
system. The ISP had attempted to stop the hacker from sending out worldwide racist
messages under the ISP=s name.
The hacker signed off with the threat, “you have yet to see true electronic terrorism. This is a promise.”
The hacker apparently never made good on his promise, but the threat of a cyberterrorist attack has many people worried.
The highly acclaimed Computers at Risk report
(1991) from the National Research Council concludes “Tomorrow’s terrorist may be able to do more with a keyboard
than with a bomb.” And Cybercrime, Cyberterrorims, and Cyberwarfare (1998)
from the Global Organized Crime Project of the Center for Strategic and International Studies in Washington, DC says “Cyberterrorists,
acting for rogue states or groups that have declared holy war against the United States, are known to be plotting America’s
demise as a superpower.”
What is Cyberterrorism?
Cyberterrorism is the convergence of cyberspace and terrorism. It refers
to unlawful attacks and threats of attack against computers, networks, and the information stored therein when done to intimidate
or coerce a government or its people in furtherance of political or social objectives.
Further, to qualify as cyberterrorism, an attack should result in violence against persons or property, or at least
cause enough harm to generate fear. Attacks that lead to death or bodily injury,
explosions, or severe economic loss would be examples. Serious attacks against
critical infrastructures could be acts of cyberterrorism, depending on their impact.
Attacks that disrupt nonessential services or that are mainly a costly nuisance would not.
Numerous scenarios have been suggested. In one, a cyberterrorist attacks
the computer systems that control a large regional power grid. Power is lost
for a sustained period of time and people die. In another, the cyberterrorist
breaks into an air traffic control system and tampers with the system. Two large
civilian aircraft collide. In a third, the cyberterrorist disrupts banks, international
financial transactions, and stock exchanges. Economic systems grind to a halt,
the public loses confidence, and destabilization is achieved. While none of these
or similar scenarios has played out, many believe it is not a question of “if” but “when.”
Terrorists in Cyberspace
Terrorists have moved into cyberspace to facilitate traditional forms of terrorism such as bombings. They use the Internet to communicate, coordinate events, and advance their agenda. While such activity
does not constitute cyberterrorism in the strict sense, it does show that terrorists have some competency using the new information
By 1996, the headquarters of terrorist
financier Osama bin Laden in Afghanistan
was equipped with computers and communications equipment. Egyptian “Afghan”
computer experts were said to have helped devise a communication network that used the Web, e-mail, and electronic bulletin
boards. Hamas activists have been said to use chat rooms and e-mail to plan operations
and coordinate activities, making it difficult for Israeli security officials to trace their messages and decode their contents. The Revolutionary Armed Forces of Columbia (FARC) uses e-mail to field inquiries from
The Web is especially popular as a medium
for reaching a global audience. For example, after the Peruvian terrorist group
Tupac Amaru stormed the Japanese Ambassador’s residence in Lima on December 17, 1996 and took 400 diplomatic, political, and military officials as
hostage, sympathizers in the United States and Canada
put up solidarity Web sites. One site included detailed drawings of the residence
and planned assault.
In February 1998, Hizbullah was operating
three Web sites: one for the central press office (www.hizbollah.org), another to describe its attacks on Israeli targets
(www.moqawama.org), and the third for news and information (www.almanar.com.lb). That
month, Clark Staten, executive director of the Emergency Response & Research Institute (ERRI) in Chicago,
testified before a U.S. Senate subcommittee that “even small terrorist groups are now using the Internet to broadcast
their message and misdirect/misinform the general population in multiple nations simultaneously.” He gave the subcommittee
copies of both domestic and international messages containing anti-American and anti-Israeli propaganda and threats, including
a widely distributed extremist call for “jihad” (holy war) against America
and Great Britain.
In June 1998, U.S. News & World Report noted that 12 of the 30 groups on the U.S. State Department=s list of terrorist organizations are on the Web. Now,
it appears that virtually every terrorist group is on the Web. Forcing them off
the Web is impossible, because they can set up their sites in countries with free-speech laws.
The government of Sri Lanka, for example, banned the
separatist Liberation Tigers of Tamil Eelam, but they have not even attempted to take down their London-based Web site.
Even in democracies, however, there are
limits to what terrorists can post on the Net. After a group of anti-abortionists
put up a Web site terrorizing doctors who performed abortions, a federal jury ordered the pages be taken down and damages
of more than $100 million paid. The Nuremberg Files site had listed the names
of about 200 abortion providers under the heading of “baby butchers.” Readers were invited to send in such personal
details as the doctors’ home addresses, license plate numbers, and the names of their children. Three doctors whose names appeared on the list were killed, and after each, the doctor’s name was
promptly crossed out. Doctors named on the site testified that they lived in
constant fear and used disguises, bodyguards, and bulletproof vests. In ordering
the site down, the federal jury said the site and “wanted” posters amounted to death threats against the doctors.
Many terrorists are using encryption to
conceal their communications and stored files, compounding the difficulties of providing effective counter-terrorism. Hamas,
for example, reportedly has used encrypted Internet communications to transmit maps, pictures, and other details pertaining
to terrorist attacks. Ramsey Yousef, a member of the international terrorist group responsible for bombing the World
Trade Center in 1994 and a Manila Air airliner in
late 1995, encrypted files on his laptop computer. The files, which U.S.
government officials decrypted, contained information pertaining to further plans to blow up eleven U.S.-owned commercial
airliners in the Far East. The Aum Shinrikyo cult, which gassed the Tokyo
subway in March 1995, killing 12 people and injuring 6,000 more, also used encryption to protect their computerized records,
which included plans and intentions to deploy weapons of mass destruction in Japan
and the United States.
Cyberspace is constantly under assault. Cyber spies, thieves, saboteurs,
and thrill seekers break into computer systems, steal personal data and trade secrets, vandalize Web sites, disrupt service,
sabotage data and systems, launch computer viruses and worms, conduct fraudulent transactions, and harass individuals and
companies. These attacks are facilitated with increasingly powerful and easy-to-use
software tools, which are readily available for free from thousands of Web sites on the Internet.
Many of the attacks are serious and costly. The ILOVEYOU virus and variants,
for example, was estimated to have hit tens of millions of users worldwide and cost billions of dollars in damage. Denial-of-service attacks against Yahoo, CNN, eBay, and other e-commerce Web sites were estimated to have
caused over a billion in losses. They also shook the confidence of business and
individuals in e-commerce.
Governments are particularly concerned with terrorist and state-sponsored attacks against the critical infrastructures
that constitute their national life support systems. The Clinton Administration
defined eight: telecommunications, banking and finance, electrical power, oil and gas distribution and storage, water supply,
transportation, emergency services, and government services.
There have been numerous attacks against
these infrastructures. Hackers have invaded the public phone networks, compromising
nearly every category of activity, including switching and operations, administration, maintenance, and provisioning (OAM&P). They have crashed or disrupted signal transfer points, traffic switches, OAM&P
systems, and other network elements. They have planted “time bomb”
programs designed to shut down major switching hubs, disrupted emergency 911 services throughout the eastern seaboard, and
boasted that they have the capability to bring down all switches in Manhattan. They have installed wiretaps, rerouted phone calls, changed the greetings on voice
mail systems, taken over voice mailboxes, and made free long-distance calls at their victims= expense -- sticking some victims with phone bills in the hundreds of thousands of dollars. When they can=t crack the
technology, they use “social engineering” to con employees into giving them access.
In March 1997, one teenage hacker penetrated
and disabled a telephone company computer that serviced the Worcester Airport
in Massachusetts. As a result,
telephone service to the Federal Aviation Administration control tower, the airport fire department, airport security, the
weather service, and various private airfreight companies was cut off for six hours.
Later in the day, the juvenile disabled another telephone company computer, this time causing an outage in the Rutland
area. The lost service caused financial damages and threatened public health
and public safety. On a separate occasion, the hacker allegedly broke into a
pharmacist=s computer and accessed files containing prescriptions.
Banks and financial systems are a popular target of cyber criminals. The
usual motive is money, and perpetrators have stolen or attempted to steal tens of millions of dollars. In one case of sabotage, a computer operator at Reuters in Hong Kong tampered with
the dealing room systems of five of the company=s bank clients. In November 1996, he programmed the systems to delete key operating system files after
a delay long enough to allow him to leave the building. When the “time
bombs” exploded, the systems crashed. They were partially restored by the
next morning, but it took another day before they were fully operational. However,
the banks said the tampering did not significantly affect trading and that neither they nor their clients experienced losses.
In another act of sabotage against a critical infrastructure, a fired employee of Chevron’s emergency alert network
disabled the firm=s alert system by hacking into computers in New
York and San Jose, California, and reconfiguring them so they=d
crash. The vandalism was not discovered until an emergency arose at the Chevron
refinery in Richmond, California, and the system could
not be used to notify the adjacent community of a noxious release. During the
10-hour period in 1992 when the system was down, thousands of people in 22 states and 6 unspecified areas of Canada
were put at risk.
An overflow of raw sewage on the Sunshine Coast
of Australia in June was linked to a 49-year-old Brisbane
man, who allegedly penetrated the Maroochy Shire Council’s computer system and used radio transmissions to create the
overflows. The man faced 370 charges that included stealing, computer hacking,
and use radio communications equipment without authority.
Government computers, particularly Department of Defense computers, are a regular target of attack. Detected attacks against unclassified DoD computers rose from 780 in 1997 to 5,844 in 1998 and 22,144 in
The most damaging and costly attacks have been conducted for reasons other than the pursuit of terrorism. As the above cases illustrate, they have been motivated by greed, thrills, ego, revenge,
and a variety of other non-ideological factors. They are properly classifified
as cybercrimes, but not cyberterrorism
Politically and Socially Motivated Cyberattacks
Terrorism is normally associated with attacks conducted in furtherance of political and social objectives. Numerous cyberattacks have been so motivated. For example,
in 1998, ethnic Tamil guerrillas swamped Sri Lankan embassies with 800 e-mails a day over a two-week period. The messages read “We are the Internet Black Tigers and we=re
doing this to disrupt your communications.” Intelligence authorities characterized it as the first known attack by terrorists
against a country=s computer systems.
Also in 1998, Spanish protestors bombarded the Institute for Global Communications (IGC) with thousands of bogus e-mail
messages. E-mail was tied up and undeliverable to the San
Francisco based ISP=s users, and support
lines were tied up with people who couldn=t get their mail. The protestors also spammed IGC staff and member accounts, clogged their Web page
with bogus credit card orders, and threatened to employ the same tactics against organizations using IGC services. They demanded that IGC stop hosting the Webs site for the Euskal
Herria Journal, a New York-based publication supporting Basque independence. Protestors
said IGC supported terrorism because a section on the Web pages contained materials on the terrorist group Fatherland and
Liberty, or ETA, which claimed responsibility for assassinations of Spanish political
and security officials, and attacks on military installations. IGC finally relented
and pulled the site because of the “mail bombings.”
During the Kosovo conflict in 1999, NATO computers were blasted with e-mail bombs and hit with denial-of-service attacks
by hacktivists protesting the NATO bombings. In addition, businesses, public
organizations, and academic institutes received highly politicized virus-laden e-mails from a range of Eastern European countries,
according to reports. Web defacements were also common. After the Chinese Embassy was accidentally bombed in Belgrade,
Chinese hacktivists posted messages such as “We won=t stop
attacking until the war stops!” on U.S. government Web
Since December 1997, the Electronic Disturbance Theater (EDT), a New York City
based activist group, has been conducting Web sit-ins against various sites in support of the Mexican Zapatistas. At a designated time, thousands of protestors point their browsers to a target site using software that
floods the target with rapid and repeated download requests. EDT=s software has also been used by animal rights groups against organizations said to abuse
animals. Electrohippies, another group of hacktivists, conducted Web sit-ins
against the WTO when they met in Seattle in late 1999. These sit-ins all require mass participation to have much effect, and thus are more suited to use by activists
than by relatively small groups of terrorists operating in secrecy.
While the above incidents were motivated by political and social reasons, whether they were sufficiently harmful or
frightening to be classified as cyberterrorism is a judgement call. To the best
of my knowledge, no attack so far has led to violence or injury to persons, although some may have intimidated their victims. Both EDT and the Electrohippies view their operations as acts of civil disobedience,
analogous to street protests and physical sit-ins, not as acts of violence or terrorism.
This is an important distinction. Most activists, whether participating
in a street march or Web sit-in, are not terrorists.
However, there are a few indications that some terrorist groups are pursuing cyberterrorism, either alone or in conjunction
with acts of physical violence. In February 1998, Clark Staten told the Senate
Judiciary Committee Subcommittee on Technology, Terrorism, and Government Information that it was believed that “members
of some Islamic extremist organizations have been attempting to develop a ‘hacker network’ to support their computer
activities and even engage in offensive information warfare attacks in the future.”
In November 1998, the Detroit News reported that Khalid Ibrahim, who
claimed to be a member of the militant Indian separatist group Harkat-ul-Ansar, had tried to buy military software from hackers
who had stolen it from Department of Defense computers they had penetrated. The
attempted purchase was discovered when an 18-year-old hacker calling himself Chameleon attempted to cash a $1,000 check from
Ibrahim. Chameleon said he did not have the software and did not give it to Ibrahim,
but Ibrahim may have obtained it or other sensitive information from one of the many other hackers he approached. Harkat-ul-Ansar
declared war on the United States following the August cruise-missile
attack on a suspected terrorist training camp in Afghanistan
run by bin Laden, which allegedly killed nine of their members.
The Provisional Irish Republican Army employed the services of contract hackers to penetrate computers in order to
acquire home addresses of law enforcement and intelligence officers, but the data was used to draw up plans to kill the officers
in a single “night of the long knives” if the British government did not meet terms for a new cease-fire. As this case illustrates, terrorists may use hacking as a way of acquiring intelligence
in support of physical violence, even if they do not use it to wreak havoc in cyberspace.
Terrorists might also engage in computer network attacks as a way of financing physical operations. For example, they could penetrate an e-commerce Web site and steal credit card numbers, conduct fraudulent
transactions against an Internet bank, or extort money from victims by threatening electronic sabotage.
To understand the potential threat of cyberterrorism, two factors must be considered: first, whether there are targets
that are vulnerable to attack that could lead to violence or severe harm, and second, whether there are actors with the capability
and motivation to carry them out.
Looking first at vulnerabilities, several studies have shown that critical infrastructures are potentially vulnerable
to cyberterrorist attack. Eligible Receiver, a Ano notice@ exercise conducted by the
Department of Defense in 1997 with support from National Security Agency penetration testing teams, found the power grid and
emergency 911 systems had weaknesses that could be exploited by an adversary using only publicly available tools on the Internet. Although neither of these systems were actually attacked, study members concluded
that service on these systems could be disrupted. Also in 1997, the President=s Commission on Critical Infrastructure Protection issued its report
warning that through mutual dependencies and interconnectedness, critical infrastructures could be vulnerable in new ways,
and that vulnerabilities were steadily increasing, while the costs of attack were decreasing.
Although many of the weaknesses in computerized systems can be corrected, it is effectively impossible to eliminate
all of them. Even if the technology itself offers good security, it is frequently
configured or used in ways that make it open to attack. In addition, there is
always the possibility of insiders, acting alone or in concert with other terrorists, misusing their access capabilities. According to Russia=s Interior Ministry Col. Konstantin Machabeli, the state-run gas monopoly,
Gazprom, was hit by hackers in 1999 who collaborated with a Gazprom insider. The
hackers were said to have used a Trojan horse to gain control of the central switchboard which controls gas flows in pipelines,
although Gazprom, the world=s largest natural gas producer and the
largest gas supplier to Western Europe, refuted the report.
Consultants and contractors are frequently in a position where they could cause grave harm. This past March, Japan=s Metropolitan Police Department reported that a software system they had procured to track
150 police vehicles, including unmarked cars, had been developed by the Aum Shinryko cult.
At the time of the discovery, the cult had received classified tracking data on 115 vehicles. Further, the cult had developed software for at least 80 Japanese firms and 10 government agencies. They had worked as subcontractors to other firms, making it almost impossible for
the organizations to know who was developing the software. As subcontractors,
the cult could have installed Trojan horses to launch or facilitate cyberterrorist attacks at a later date. Fearing a Trojan horse of their own, last February, the U.S. State Department sent an urgent cable to about
170 embassies asking them to remove software, which they belatedly realized had been written by citizens of the former Soviet
If we take as given that critical infrastructures are vulnerable to a cyberterrorist attack, then the question becomes
whether there are actors with the capability and motivation to carry out such an operation.
While many hackers have the knowledge, skills, and tools to attack computer systems, they generally lack the motivation
to cause violence or severe economic or social harm. Conversely, terrorists who are motivated to cause violence seem to lack
the capability or motivation to cause that degree of damage in cyberspace.
In August 1999, the Center for the Study of Terrorism and Irregular Warfare at the Naval Postgraduate School in Monterey,
California, issued a report titled “Cyberterror: Prospects and Implications.”
Their objective was to articulate the demand side of terrorism. Specifically,
they assessed the prospects of terrorist organizations pursuing cyberterrorism. They
concluded that the barrier to entry for anything beyond annoying hacks is quite high, and that terrorists generally lack the
wherewithal and human capital needed to mount a meaningful operation. Cyberterrorism,
they argued, was a thing of the future, although it might be pursued as an ancillary tool.
The Monterey team defined three levels of cyberterror capability. First is simple-unstructured: the capability to conduct basic hacks against individual
systems using tools created by someone else. The organization possesses little
target analysis, command and control, or learning capability.
Second is advanced-structured: the capability to conduct more sophisticated attacks against multiple systems or networks
and possibly, to modify or create basic hacking tools. The organization possesses
an elementary target analysis, command and control, and learning capability.
Third is complex-coordinated: the capability for a coordinated attacks capable of causing mass-disruption against integrated,
heterogeneous defenses (including cryptography). The organization has the ability
to create sophisticated hacking tools. They possess a highly capable target analysis,
command and control, and organization learning capability.
The Monterey team estimated that it would take a group starting from scratch
2-4 years to reach the advanced-structured level and 6-10 years to reach the complex-coordinated level, although some groups
might get there in just a few years or turn to outsourcing or sponsorship to extend their capability.
The study examined five terrorist group types: religious, New Age, ethno-nationalist separatist, revolutionary, and
far-right extremists. They determined that only the religious groups are likely
to seek the most damaging capability level, as it is consistent with their indiscriminate application of violence. New Age or single issue terrorists, such as the Animal Liberation Front, pose the most immediate threat,
however, such groups are likely to accept disruption as a substitute for destruction.
Both the revolutionary and ethno-nationalist separatists are likely to seek an advanced-structured capability. The far-right extremists are likely to settle for a simple-unstructured capability,
as cyberterror offers neither the intimacy nor cathartic effects that are central to the psychology of far-right terror. The study also determined that hacker groups are psychologically and organizationally
ill-suited to cyberterrorism, and that it would be against their interests to cause mass disruption of the information infrastructure.
Thus, at this time, cyberterrorism does not seem to pose an imminent threat.
This could change. For a terrorist, it would have some advantages over physical methods. It could be conducted remotely and anonymously, and it would not require the handling of explosives or
a suicide mission. It would likely garner extensive media coverage, as journalists
and the public alike are fascinated by practically any kind of computer attack. Indeed
cyberterrorism could be immensely appealing precisely because of the tremendous attention given to it by the government and
Cyberterrorism also has its drawbacks. Systems are complex, so it may
be harder to control an attack and achieve a desired level of damage than using physical weapons. Unless people are injured, there is also less drama and emotional appeal.
Further, terrorists may be disinclined to try new methods unless they see their old ones as inadequate, particularly
when the new methods require considerable knowledge and skill to use effectively. Terrorists
generally stick with tired and true methods. Novelty and sophistication of attack
may be much less important than assurance that a mission will be operationally successful.
Indeed, the risk of operational failure could be a deterrent to terrorists. For
now, the truck bomb poses a much greater threat than the logic bomb.
The next generation of terrorists will grow up in a digital world, with ever more powerful and easy-to-use hacking
tools at their disposal. They might see greater potential for cyberterrorism
than the terrorists of today, and their level of knowledge and skill relating to hacking will be greater. Hackers and insiders might be recruited by terrorists or become self-recruiting cyberterrorists, the Timothy
McVeigh=s of cyberspace. Some
might be moved to action by cyber policy issues, making cyberspace an attractive venue for carrying out an attack. Cyberterrorism could also become more attractive as the real and virtual worlds become more closely coupled,
with a greater number of physical devices attached to the Internet. Some of these
may be remotely controlled. Terrorists, for example, might target robots used
in telesurgery. Unless these systems are carefully secured, conducting an operation
that physically harms someone may be easy as penetrating a Web site is today.
Although the violent pursuit of political goals using exclusively electronic methods is likely to be at least a few
years into the future, the more general threat of cybercrime is very much a part of the digital landscape today. In addition to cyberattacks against digital data and systems, many people are being terrorized on
the Internet today with threats of physical violence. On-line stalking, death
threats, and hate messages are abundant. These crimes are serious and must be
addressed. In so doing, we will be in a better position to prevent and respond
to cyberterrorism if and when the threat becomes more serious.
Dorothy E. Denning is
professor of computer science at Georgetown University and Director of the Georgetown Institute for Information Assurance. She has been working on cyberspace threats and defenses for almost thirty years and
is author of Information Warfare and Security (Addison Wesley, 1998).