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.

Aliases

• Ah

• David-1173

• Tuesday

Characteristics

Jerusalem.Ah is a stealth, memory resident, file infecting virus. It infects .COM files. Jerusalem.Ah is believed to have been created by the same person as several other viruses from Italy, including Smack and Enigma.

Upon infection, Jerusalem.Ah becomes memory resident at the top of system memory, but below the 640K DOS boundary. Interrupts 08 and 21 are hooked by the virus.

Once Jerusalem.Ah is memory resident, it infects .COM files over 1K in length as they are executed.

Additional Comments:
The Ah, or Tuesday, Virus was received in May, 1991. Ah is based on the V1024 virus, its origin is Italy. Ah is a very buggy virus which infects .COM programs. When the first program infected with Ah is executed, Ah will install itself memory resident at the top of system memory, but below the 640K DOS boundary. Total system and available free memory, as indicated by the DOS CHKDSK program, will decrease by 1,216 bytes. Interrupts 08 and 21 will be hooked by the virus. After Ah is memory resident, it will infect .COM programs over 1K in length when they are executed. Infected programs will increase in size by 1,173 bytes, though the file length increase will be hidden if Ah is resident. Their date and time in the DOS directory will appear to be unaltered, though if the program's original time was 12:00a, it will now be blank. The virus will be located at the beginning of infected programs. Systems infected with Ah will experience frequent system hangs. These hangs occur when the user attempts to execute a .COM program which is infected with Ah. They may also occur when the virus attempts to infect an uninfected program. System hangs occur so frequently with Ah that the virus is very noticeable. The Ah virus activates on Tuesdays, at which time it will attempt to format the first few tracks of the system hard disk. Programs infected with Ah can be easily identified as they will contain the following text strings: "(C) David Grant Virus Research 1991 PCVRF Disribuite this virus freely!!! ...ah...John...Fuck You!" Ah is believe to have been created by the same person as several other viruses from Italy, including Smack and Enigma. David Grant and the PCVRF had nothing to do with its creation. Known variant(s) of Ah are:

Symptoms

Files infected with Jerusalem.Ah can be easily identified as they contain the following text strings:

"(C) David Grant Virus Research 1991 PCVRF Disribuite this virus freely!!! ...ah...John...'Expletive' You!"

David Grant and the PCVRF had nothing to do with its creation.

Systems infected with Jerusalem.Ah experience frequent system hangs, when the user attempts to execute an infected .COM file. System hangs also occur when the virus attempts to infect an uninfected file.

The Jerusalem.Ah virus activates on Tuesdays, at which time it attempts to format the first few tracks of the system hard disk.

Total system and available free memory decreases by 1,216 bytes. Infected files increase in size by 1,173 bytes, the file length increase is hidden when Jerusalem.Ah is memory resident (Stealth techniques). The file's date and time in the DOS directory are not altered, except when the file's original time was 12:00a, it is changed to a blank field. The virus is located at the beginning of infected files.

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

• Ah-B

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.

Aliases

• Ah

• David-1173

• Tuesday

Characteristics

Characteristics -

Jerusalem.Ah is a stealth, memory resident, file infecting virus. It infects .COM files. Jerusalem.Ah is believed to have been created by the same person as several other viruses from Italy, including Smack and Enigma.

Upon infection, Jerusalem.Ah becomes memory resident at the top of system memory, but below the 640K DOS boundary. Interrupts 08 and 21 are hooked by the virus.

Once Jerusalem.Ah is memory resident, it infects .COM files over 1K in length as they are executed.

Additional Comments:
The Ah, or Tuesday, Virus was received in May, 1991. Ah is based on the V1024 virus, its origin is Italy. Ah is a very buggy virus which infects .COM programs. When the first program infected with Ah is executed, Ah will install itself memory resident at the top of system memory, but below the 640K DOS boundary. Total system and available free memory, as indicated by the DOS CHKDSK program, will decrease by 1,216 bytes. Interrupts 08 and 21 will be hooked by the virus. After Ah is memory resident, it will infect .COM programs over 1K in length when they are executed. Infected programs will increase in size by 1,173 bytes, though the file length increase will be hidden if Ah is resident. Their date and time in the DOS directory will appear to be unaltered, though if the program's original time was 12:00a, it will now be blank. The virus will be located at the beginning of infected programs. Systems infected with Ah will experience frequent system hangs. These hangs occur when the user attempts to execute a .COM program which is infected with Ah. They may also occur when the virus attempts to infect an uninfected program. System hangs occur so frequently with Ah that the virus is very noticeable. The Ah virus activates on Tuesdays, at which time it will attempt to format the first few tracks of the system hard disk. Programs infected with Ah can be easily identified as they will contain the following text strings: "(C) David Grant Virus Research 1991 PCVRF Disribuite this virus freely!!! ...ah...John...Fuck You!" Ah is believe to have been created by the same person as several other viruses from Italy, including Smack and Enigma. David Grant and the PCVRF had nothing to do with its creation. Known variant(s) of Ah are:

Symptoms

Symptoms -

Files infected with Jerusalem.Ah can be easily identified as they contain the following text strings:

"(C) David Grant Virus Research 1991 PCVRF Disribuite this virus freely!!! ...ah...John...'Expletive' You!"

David Grant and the PCVRF had nothing to do with its creation.

Systems infected with Jerusalem.Ah experience frequent system hangs, when the user attempts to execute an infected .COM file. System hangs also occur when the virus attempts to infect an uninfected file.

The Jerusalem.Ah virus activates on Tuesdays, at which time it attempts to format the first few tracks of the system hard disk.

Total system and available free memory decreases by 1,216 bytes. Infected files increase in size by 1,173 bytes, the file length increase is hidden when Jerusalem.Ah is memory resident (Stealth techniques). The file's date and time in the DOS directory are not altered, except when the file's original time was 12:00a, it is changed to a blank field. The virus is located at the beginning of infected files.

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 -

• Ah-B