Null Set

This page shows details and results of our analysis on the malware Null Set

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 DAT

4002 (1998-12-02)

Updated DAT

4002 (1998-12-02)

Minimum Engine

5400.1158

File Length

733 Bytes

Description Added

1992-02-15

Description Modified

1992-02-15

Malware Proliferation

Characteristics

Null Set is a file infecting virus. It does not become memory resident. It infects .COM files, including COMMAND.COM.

Each time a file infected with the Null Set virus is executed, the virus infects one previously uninfected .COM file over approximately 700 bytes in size, in the current directory.

Null Set does not appear to do anything besides replicate.

Additional Comments:
The Null Set virus was submitted in February, 1992. It is from the United States. Null Set is a non-resident direct action infector of .COM programs, including COMMAND.COM. When a program infected with the Null Set virus is executed, the virus will search the current directory to locate the first previously uninfected .COM program over approximately 700 bytes in size. If an uninfected .COM program is located, the virus will infected it. Programs infected with the Null Set virus will have a file length increase of 733 bytes. The virus will be located at the end of the program. The file's date and time in the DOS disk directory listing will not be altered. Null Set doesn't appear to do anything besides replicate.

Symptoms

Files infected with the Null Set virus have a file length increase of 733 bytes. The virus is located at the end of the 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