ActiveX controls are software modules based on Microsoft's Component Object Model (COM) architecture. They add functionality to software applications by seamlessly incorporating pre-made modules with the basic software package. Modules can be interchanged but still appear as parts of the original software. On the Internet, ActiveX controls can be linked to Web pages and downloaded by an ActiveX-compliant browser. ActiveX controls turn Web pages into software pages that perform like any other program launched from a server. ActiveX controls can have full system access. In most instances this access is legitimate, but one should be cautious of malicious ActiveX applications.

Algorithm

A sequence of steps needed to solve logical or mathematical problems. Certain cryptographic algorithms are used to encrypt or decrypt data files and messages and to sign documents digitally.

Anti-antivirus Virus

Anti-antivirus viruses attack, disable or infect specific anti-virus software. Also: Retrovirus

Anti-virus Software

Anti-virus software scans a computer's memory and disk drives for viruses. If it finds a virus, the application informs the user and may clean, delete or quarantine any files, directories or disks affected by the malicious code. Also: Anti-virus Scanner

Antivirus Virus

Antivirus viruses specifically look for and remove other viruses.

Applet

Any miniature application transported over the Internet, especially as an enhancement to a Web page. Authors often embed applets within the HTML page as a foreign program type.

Java applets are usually only allowed to access certain areas of the user's system. Computer programmers often refer to this area as the sandbox.

Armored Virus

An armored virus tries to prevent analysts from examining its code. The virus may use various methods to make tracing, disassembling and reverse engineering its code more difficult.

ASCII

American Standard Code for Information Interchange. Usually refers to coding system that assigns numerical values to characters such as letter, numbers, punctuation, and other symbols.

Basic ASCII allows only 7 bits per character (for a total of 128 characters). The first 32 characters are "unprintable" (line feed, form feed, etc.). Extended ASCII adds an additional 128 characters that vary between computers, programs and fonts. Computers use these extra characters for accented letters, graphical characters or other special symbols.

ASCII Files

ASCII files are usually text files consisting of only ASCII characters. With effort, it is possible to write program files consisting only of printable characters (See: EICAR Standard Anti-virus Test File). Windows batch (BAT) files and Visual Basic Script (See Also: Batch Files, VBS) files are also typically pure text, and program files.

Because of the danger macro viruses can pose, using ASCII files in e-mail communications may by less risky. While it is possible for ASCII files to contain program code, and thus to contain viruses, ASCII files let you control both content and layout exactly, ensuring your e-mail is legible by the most e-mail programs.

Attack

An attempt to subvert or bypass a system's security. Attacks may be passive or active. Active attacks attempt to alter or destroy data. Passive attacks try to intercept or read data without changing it. See Also: Brute Force Attack, Denial of Service, Hijacking, Password Attacks, Password Sniffing

Attributes

Characteristics assigned to all files and directories. Attributes include: Read Only, Archive, Hidden or System.