Glossary of Computer Security

The following is a list of terms that describe computer security threats and measures used to protect against them.

• adware - A program that generates pop-up advertisements based on information it collects about a user's browser patterns. When adware is installed without the user's consent, it is considered spyware.
• encryption - A security measure that converts messages into code, so that they can only be read by the sender and the intended recipient who knows how to decode the message.
• firewall - A system used to protect systems and networks from unauthorized access.
• malware - A general term for malicious software that is specifically designed to attack or damage a computer. Viruses, Trojan horses, and worms are all types of malware.
• password attack - An attempt to steal passwords using a password cracking program.
• password sniffing - An attempt to steal passwords by using a program that scans all the messages traversing a network looking for passwords.
• PGP - A program used for signing, encrypting, and decrypting emails. PGP is an acronym for Pretty Good Privacy.
• spam - electronic junk mail, usually email advertising.
• spam filter - A feature, usually part of an email program, which lets you block specific email messages. Spam filters can be set to block incoming mail from particular senders.
• spim - Spam sent via instant messaging.
• spyware - A program that collects information about the user and relays it to the originator. Spyware can be installed without the user's knowledge when installing new software, especially when it is freeware, or from clicking pop-up ads or display banners.
• trojan horse or trojan - An unauthorized program hidden inside a legitimate program. It usually does some harm to the computer system while the host program appears to be performing normally. It is named after the famous Trojan horse of Greek mythology.
• virus - A computer program that reproduces itself by attaching to another program. It needs another program to continue spreading, unlike a worm. The most common way that a virus is spread is via an attachment to an email message. Viruses can damage data or change data without the user's knowledge.
• worm - A self-replicating computer program. It does not require any user intervention and does not need to be attached to any other program, unlike a virus. It uses the network to send copies of itself to other computers. Most worms corrupt data and change files on the targeted systems, along with consuming network bandwidth.
• zombie - A computer that is under the control of a malicious hacker.