McAfee > Theat Center > Virus Detail Page

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.

Characteristics

Chaos.1241 is a memory resident, file infecting virus. It infects .COM files, including COMMAND.COM.

Upon infection, the Chaos.1241 virus becomes memory resident as a low system memory Terminate-and-Stay (TSR) of 1,584 bytes. It hooks interrupt 21. Its TSR may appear as "Command data" or as part of the command interpreter in some memory mapping utilities.

Once the Chaos.1241 virus is memory resident, it infects .COM files as they are executed.

It is not known what Chaos.1241 does besides replicate.

Additional Comments:
The 1241 virus was received in December, 1991. Its origin is unknown. This virus is a memory resident infector of .COM programs, including COMMAND.COM. When the first 1241 infected program is executed, the 1241 virus will install itself memory resident as a low system memory TSR of 1,584 bytes, hooking interrupt 21. Its TSR may appear as "Command data" or as part of the command interpretor in some memory mapping utilities. Once the 1241 virus is memory resident, it will infect .COM programs when they are executed. If COMMAND.COM is executed, it will become infected as well. 1241 infected files will have a file length increase of 1,241 bytes with the virus being located at the end of the infected file. There will be no change to the file's date and time in the DOS disk directory listing. It is unknown what 1241 does besides replicate.

Symptoms

Chaos.1241 infected files have a file length increase of 1,241 bytes. The virus is located at the end of the infected file. There is no change to the file's date and time in the DOS disk directory listing.

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:

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

Variants

N/A

All Information

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.

Characteristics

Characteristics -

Chaos.1241 is a memory resident, file infecting virus. It infects .COM files, including COMMAND.COM.

Upon infection, the Chaos.1241 virus becomes memory resident as a low system memory Terminate-and-Stay (TSR) of 1,584 bytes. It hooks interrupt 21. Its TSR may appear as "Command data" or as part of the command interpreter in some memory mapping utilities.

Once the Chaos.1241 virus is memory resident, it infects .COM files as they are executed.

It is not known what Chaos.1241 does besides replicate.

Additional Comments:
The 1241 virus was received in December, 1991. Its origin is unknown. This virus is a memory resident infector of .COM programs, including COMMAND.COM. When the first 1241 infected program is executed, the 1241 virus will install itself memory resident as a low system memory TSR of 1,584 bytes, hooking interrupt 21. Its TSR may appear as "Command data" or as part of the command interpretor in some memory mapping utilities. Once the 1241 virus is memory resident, it will infect .COM programs when they are executed. If COMMAND.COM is executed, it will become infected as well. 1241 infected files will have a file length increase of 1,241 bytes with the virus being located at the end of the infected file. There will be no change to the file's date and time in the DOS disk directory listing. It is unknown what 1241 does besides replicate.

Symptoms

Symptoms -

Chaos.1241 infected files have a file length increase of 1,241 bytes. The virus is located at the end of the infected file. There is no change to the file's date and time in the DOS disk directory listing.

Method of Infection

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 -

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:

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

Variants -

N/A