- is a program written with malicious intent and sent out by attackers. The virus is transferred to another computer through e-mail, file transfers, and instant messaging. The virus hides by attaching itself to a file on the computer. When the file is accessed, the virus executes and infects the computer. A virus has the potential to corrupt or even delete files on your computer, use your e-mail to spread itself to other computers, or even erase your entire hard drive.
- Some viruses can be exceptionally dangerous. The most damaging type of virus is used to record keystrokes. These viruses can be used by attackers to harvest sensitive information, such as passwords and credit card numbers. Viruses may even alter or destroy information on a computer. Stealth viruses can infect a computer and lay dormant until summoned by the attacker.
is a self-replicating program that is harmful to networks. A worm uses the network to duplicate its code to the hosts on a network, often without any user intervention. It is different from a virus because a worm does not need to attach to a program to infect a host. Even if the worm does not damage data or applications on the hosts it infects, it is harmful to networks because it consumes bandwidth.
is technically a worm. The Trojan does not need to be attached to other software. Instead, a Trojan threat is hidden in software that appears to do one thing, and yet behind the scenes it does another. Trojans are often disguised as useful software. The Trojan program can reproduce like a virus and spread to other computers. Computer data damage and production loss could be significant. A technician may be needed to perform the repairs, and employees may lose or have to replace data. An infected computer could be sending critical data to competitors, while at the same time infecting other computers on the network.
is a software program that displays advertising on your computer. Adware is usually distributed with downloaded software. Most often, adware is displayed in a popup window. Adware popup windows are sometimes difficult to control and will open new windows faster than users can close them.
Grayware or malware
is a file or program other then a virus that is potentially harmful. Many grayware attacks are phishing attacks that try to persuade the reader to unknowingly provide attackers with access to personal information. As you fill out an online form, the data is sent to the attacker. Grayware can be removed using spyware and adware removal tools.
a type of grayware, is similar to adware. It is distributed without any user intervention or knowledge. Once installed, the spyware monitors activity on the computer. The spyware then sends this information to the organization responsible for launching the spyware.
is a form of social engineering where the attacker pretends to represent a legitimate outside organization, such as a bank. A potential victim is contacted via e-mail. The attacker might ask for verification of information, such as a password or username, to supposedly prevent some terrible consequence from occurring.
Denial of service (DoS)
is a form of attack that prevents users from accessing normal services, such as e-mail and a web server, because the system is busy responding to abnormally large amounts of requests. DoS works by sending enough requests for a system resource that the requested service is overloaded and ceases to operate.
Name Two Common DoS attacks
- Ping of death – A series of repeated, larger than normal pings that crash the receiving computer
- E-mail bomb – A large quantity of bulk e-mail that overwhelms the e-mail server preventing users from accessing it
Distributed DoS (DDoS)
is another form of attack that uses many infected computers, called zombies, to launch an attack. With DDoS, the intent is to obstruct or overwhelm access to the targeted server. Zombie computers located at different geographical locations make it difficult to trace the origin of the attack.