D-F

Decompiler

A type of program that reconstructs a program's original source code from an executable file. Decompilers exist for Visual Basic, Java, and other programming languages. See Disassembler.

Delphi

Rapid-application development tool based on the Pascal programming language. Often used to write remote access Trojan horse programs. See RAT and Visual Basic.

Denial-of-service attack

The tying up of a computer's resources to prevent its use by others. Often abbreviated as DoS.

DES

(Data Encryption Standard) An encryption method. DES can be cracked and is thus considered useless for encrypting valuable or sensitive information. See AES.

Desktop-monitoring program

Program designed to spy and record the activities of a person on a computer without his or her knowledge. See Spyware.

Dictionary attack

A way of finding a password by trying a list of common passwords such as Star Trek lingo, names of cars, or titles of popular movies.

Direct action virus

A virus that does something immediately each time you run it, such as attack your hard disk or display a message on the screen.

Disassembler

A program that generates assembly language source code from an executable program file. See Assembly language and Decompiler.

Email bombing

Clogging up an email account by sending a large number of email messages or several huge files. See Fax bombing and Phone call flooding.

Encryption

A method of scrambling data to make it unreadable by others. See AES and DES.

EXE file

A common name for a file that contains a program such as a word processor or a game. An EXE file is a relocatable program that can be used to store larger programs.

False negative

When a program, such as an antivirus or anti–Trojan horse program, fails to detect a result. When an anti-virus program fails to detect a legitimate virus, that result is called a false negative.

False positive

When a program, such as an antivirus or anti–Trojan horse program, incorrectly claims an error. When an anti-virus program incorrectly identifies a virus where none exists, the result is called a false positive.

Fast infector

A type of virus that infects program files whenever the computer loads or examines the virus file.

FAT

(file allocation table) Part of the disk that contains information about the size and location of all the other files on the disk. Each time you format a disk, it creates two identical FATs, which store information on the clusters used by each file stored on the disk. If your disk's FAT gets messed up, the files are still on the disk, but your computer will no longer be able to find or use them.

Fax bombing

Sending multiple messages to a fax machine to prevent others from using it. See Email bombing and Phone call flooding.

File infector

Another name for program infectors.

Firewall

Utility designed to keep intruders out of a network or individual computer.

Flooder

A malicious program designed to overwhelm a target computer with more data than it can handle. See Denial-of-service attack and Email bombing.

Forensics

The science of recovering deleted files for evidence.

Fortress phone

Slang name for a pay phone, referring to its extensive defenses designed to keep people from breaking into it.

Freeware

Software that can be copied, distributed, and given away without payment of any kind. See Adware and Shareware.