Threat Detail

  • Malware Type: Virus
  • Malware Sub-type: File Infector
  • Protection Added: 1991-10-15

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

5400.1158

File Length

2,600 Bytes

Description Added

1991-10-15

Description Modified

1991-10-15

Malware Proliferation

Ada is a memory resident, file infecting virus. It infects .COM files, including COMMAND.COM.

Upon infection, Ada becomes memory resident as a low system memory Terminate-and-Stay Resident (TSR). Interrupts 08, 13, and 21 are hooked by the virus.

Once Ada is memory resident, it infects .COM files as they are executed.

Additional Comments:
The Ada virus was discovered in Argentina in October, 1991. Ada is a memory resident infector of .COM files, including COMMAND.COM. The first time a program infected with the Ada virus is executed, Ada will install itself memory resident as a low system memory TSR. Available system memory as measured by the DOS CHKDSK program will have decreased by 21,296 to 21,312 bytes. Interrupts 08, 13, and 21 will be hooked by the virus. Once Ada is memory resident, it will infect .COM programs when they are executed. If COMMAND.COM is executed, it will also become infected. Programs infected with Ada will have a file size increase of 2,600 bytes with the virus being located at the beginning of infected files. There will be no visible change in the program's date and time in the DOS disk directory. The following text strings can be found in infected programs: "COMMAND.COM" "PCCILLIN.COM" "PCCILLIN.IMG" "HATI-HATI !! ADA VIRUS DISINI !!Delete" Systems infected with Ada experience a slow clicking sound being emitted from the system speaker. This clicking will occasionally change in pitch. The user may also receive a "Disk full" error even though the disk the user is attempting to write to is not actually full.

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.

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.
The following text strings are found in infected files:

"COMMAND.COM"
"PCCILLIN.COM"
"PCCILLIN.IMG"
"HATI-HATI !! ADA VIRUS DISINI !!Delete"

Systems infected with Ada experience a slow clicking sound, emitted from the system speaker. This clicking occasionally changes in pitch. The user may also receive a "Disk full" error even though the disk the user is attempting to write to is not actually full.

Available system memory as measured by the DOS CHKDSK program decreases by 21,296 to 21,312 bytes. Files infected with Ada have a file size increase of 2,600 bytes. The virus is located at the beginning of infected files. There are no visible changes in the file's date and time in the DOS disk directory.