Macro

A macro is a series of instructions designed to simplify repetitive tasks within a program such as Microsoft Word, Excel or Access. Macros execute when a user opens the associated file. Microsoft's latest macro programming language is simple to use, powerful, and not limited to Word documents. Macros are in mini-programs and can be infected by viruses. See Also: Macro Virus

Macro Virus

A macro virus is a malicious macro. Macro viruses are written a macro programming language and attach to a document file (such as Word or Excel). When a document or template containing the macro virus is opened in the target application, the virus runs, does its damage and copies itself into other documents. Continual use of the program results in the spread of the virus.

Mailbomb

n. Excessively large e-mail (typically many thousands of messages) or one large message sent to a user's e-mail account, for the purpose of crashing the system, or preventing genuine messages from being received.

v. To send a mailbomb.

Malicious Code

A piece of code designed to damage a system or the data it contains, or to prevent the system from being used in its normal manner.

Malware

A generic term used to describe malicious software such as: viruses, trojan horses, malicious active content, etc.

Mapped Drives

Network drives assigned local drive letters and locally accessible. For example, the directory path \\MAIN\JohnDoe\ might be mapped as drive G: on a computer.

Master Boot Record

The 340-byte program located in the master boot sector. This program reads the partition table, determines what partition to boot and transfers control to the program stored in the first sector of that partition. There is only one master boot record on each physical hard disk. Also: MBR, Partition Table; See Also: Boot Record

Master Boot Sector

The first sector of a hard disk. This sector is located at sector 1, head 0, track 0. The sector contains the master boot record. See Also: Master Boot Record

Master Boot Sector Virus

Master boot sector viruses infect the master boot sector of hard disks, though they spread through the boot record of floppy disks. The virus stays in memory, waiting for DOS to access a floppy disk. It then infects the boot record on each floppy disk DOS accesses.

Also: Master Boot Record Virus; See Also: Boot Record

MBR

See: Master Boot Record

Memory-resident Virus

A memory-resident virus stays in memory after it executes and infects other files when certain conditions are met. In contrast, non-memory-resident viruses are active only while an infected application runs.

MP3 File

Moving Picture Experts Group Audio Layer 3 File. MP3 files are highly compressed audio tracks, and are very popular on the Internet. MP3 files are not programs, and viruses cannot infect them. This file type has the extension MP3.

MS-DOS

The Microsoft Disk Operating System. The operating system Microsoft developed for the IBM platform before Windows. Windows 3.x, 95 and 98 rely heavily on MS-DOS and can execute most MS-DOS commands.

Multipartite Virus

Multipartite viruses use a combination of techniques including infecting documents, executables and boot sectors to infect computers. Most multipartite viruses first become resident in memory and then infect the boot sector of the hard drive. Once in memory, multipartite viruses may infect the entire system.

Removing multipartite viruses requires cleaning both the boot sectors and any infected files. Before you attempt the repair, you must have a clean, write-protected Rescue Disk.

Mutant

See: Variant

Mutating Virus

A mutating virus changes, or mutates, as it progresses through its host files making disinfection more difficult. The term usually refers to viruses that intentionally mutate, though some experts also include non-intentionally mutating viruses. See Also: Polymorphic Virus