Computer attack

A computer attack may be defined as actions directed against computer systems to disrupt equipment operations, change processing control, or corrupt stored data. Different attack methods target different vulnerabilities and involve different types of weapons, and several may be within the current capabilities of some terrorist groups. Three different methods of attack have been identified, based on the effects of the weapons used. However, as technology evolves, distinctions between these methods may begin to blur.

Department of Defense officials have stated that while CNA and EA threats are “less likely” than physical attacks, they could actually prove more damaging because they involve disruptive technologies that might generate unpredictable consequences or give an adversary unexpected advantages.
 * A physical attack involves conventional weapons directed against a computer facility or its transmission lines;
 * An electronic attack (EA) involves the use the power of electromagnetic energy as a weapon, more commonly as an electromagnetic pulse (EMP) to overload computer circuitry, but also in a less violent form, to insert a stream of malicious code directly into an enemy's microwave radio transmission; and
 * A computer network attack (CNA), usually involves malicious code used as a weapon to infect enemy computers to exploit a weakness in software, in the system configuration, or in the computer security practices of an organization or computer user. Other forms of CNA are enabled when an attacker uses stolen information to enter restricted computer systems.

Characteristics of Physical Attacks
A physical attack disrupts the reliability of computer equipment and availability of data. A physical attack is implemented either through use of conventional weapons, creating heat, blast, and fragmentation, or through direct manipulation of wiring or equipment, usually after gaining unauthorized physical access.

Characteristics of Electronic Attack (EA)
Electronic attack, most commonly referred to as an electromagnetic pulse (EMP), disrupts the reliability of electronic equipment through generating instantaneous high energy that overloads circuit boards, transistors, and other electronics. EMP effects can penetrate computer facility walls where they can erase electronic memory, upset software, or permanently disable all electronic components.

Some assert that little has been done by the private sector to protect against the threat from electromagnetic pulse, and that commercial electronic systems in the United States could be severely damaged by limited range, small-scale, or portable electromagnetic pulse devices. Some military experts have stated that the United States is perhaps the nation most vulnerable to electromagnetic pulse attack.

Characteristics of Cyberattack (CNA)
A computer network attack (CNA), or “cyberattack,” disrupts the integrity or authenticity of data, usually through malicious code that alters program logic that controls data, leading to errors in output. Computer hackers opportunistically scan the Internet looking for computer systems that are misconfigured or lacking necessary security software. Once infected with malicious code, a computer can be remotely controlled by a hacker who may, via the Internet, send commands to spy on the contents of that computer or attack and disrupt other computers.

Cyberattacks usually require that the targeted computer have some pre-existing system flaw, such as a software error, a lack of antivirus protection, or a faulty system configuration, for the malicious code to exploit. However, as technology evolves, this distinguishing requirement of CNA may begin to fade. For example, some forms of EA can now cause effects nearly identical to some forms of CNA. For example, at controlled power levels, the transmissions between targeted microwave radio towers can be hijacked and specially designed viruses, or altered code, can be inserted directly into the adversary’s digital network.