Keyboard Bug

This page shows details and results of our analysis on the malware Keyboard Bug

Overview

This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.


Minimum Engine

5600.1067

File Length

1,598-1,620 Bytes

Description Added

1992-01-15

Description Modified

1992-01-15

Malware Proliferation

Characteristics

Keyboard Bug is a memory resident, file infecting virus. It infects .COM and .EXE files, but does not infect COMMAND.COM.

Upon infection, the Keyboard Bug virus becomes memory resident at the top of system memory but below the 640K DOS boundary. Interrupt 12's return is not moved. Interrupts 01, 03, 1C, and AC are hooked by the virus in memory.

Once the Keyboard Bug virus is memory resident, it infects .COM and .EXE files, as they are executed.

Additional Comments:
The Keyboard Bug, or Keyboard Bug-1596, virus was submitted in January, 1992. Its origin is unknown. Keyboard Bug is a memory resident infector of .COM and .EXE programs, but does not infect COMMAND.COM. The first time a program infected with Keyboard Bug is executed, the Keyboard Bug virus will install itself memory resident at the top of system memory but below the 640K DOS boundary. Interrupt 12's return will not have been moved. Total system and available free memory, as indicated by the DOS CHKDSK program, will have decreased by 1,616 bytes. Interrupts 01, 03, 1C, and AC will be hooked by the virus in memory. Once the Keyboard Bug virus is memory resident, it will infect .COM and .EXE programs, other than COMMAND.COM, when they are executed. .COM files will have a file length increase of 1,620 bytes. .EXE files will have a file length increase of 1,598 to 1,612 bytes in length. In both cases, the virus will be located at the end of the infected program. The file's date and time in the DOS disk directory listing will not have been altered. Systems infected with the Keyboard Bug virus will experience intermittent interference with keyboard input due to the virus adding bursts of random characters to the keyboard buffer. System hangs may also occur, in particular if the user attempts to copy programs using the DOS COPY command. Known variant(s) of Keyboard Bug are:

Symptoms

Systems infected with the Keyboard Bug virus may experience intermittent interference with keyboard input due to the virus adding bursts of random characters to the keyboard buffer. System hangs may also occur, in particular if the user attempts to copy files using the DOS COPY command.

Total system and available free memory decreases by 1,616 bytes. Infected .COM files have a file length increase of 1,620 bytes. Infected .EXE files have a file length increase of 1,598 to 1,612 bytes in length. In both cases, the virus is located at the end of the infected file. The file's date and time in the DOS disk directory listing are not altered.

Method of Infection

The only way to infect a computer with a file infecting virus is to execute an infected file on the computer. The infected file may come from a multitude of sources including: floppy diskettes, downloads through an online service, network, etc. Once the infected file is executed, the virus may activate.

Removal

All Users :
Script,Batch,Macro and non memory-resident:
Use current engine and DAT files for detection and removal.

PE,Trojan,Internet Worm and memory resident :
Use specified engine and DAT files for detection. To remove, boot to MS-DOS mode or use a boot diskette and use the command line scanner:

SCANPM /ADL /CLEAN /ALL

Additional Windows ME/XP removal considerations


Users should not trust file icons, particularly when receiving files from others via P2P clients, IRC, email or other mediums where users can share files.

AVERT Recommended Updates :

* Office2000 Updates

* Malformed Word Document Could Enable Macro to Run Automatically (Information/Patch )

* scriptlet.typelib/Eyedog vulnerability patch

* Outlook as an email attachment security update

* Exchange 5.5 post SP3 Information Store Patch 5.5.2652.42 - this patch corrects detection issues with GroupShield

For a list of attachments blocked by the Outlook patch and a general FAQ, visit this link .
Additionally, Network Administrators can configure this update using an available tool - visit this link for more information .

It is very common for macro viruses to disable options within Office applications for example in Word, the macro protection warning commonly is disabled. After cleaning macro viruses, ensure that your previously set options are again enabled.

Variants

KeyboardBug-914
KeyboardBug-1720
KeyboardBug-1724