Virus Profile: W97M/Obeso

Threat Search
Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 1/4/2001
Date Added: 1/19/2001
Origin: Unknown
Length: N/A
Type: Virus
Subtype: Macro
DAT Required: 4116
Removal Instructions


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.

Indication of Infection

- Presence of the registry key previously mentioned
- Absence of the TOOLS|MACRO and VIEW menus in Word
- Screen resolution reverting to 320x200

Methods of Infection

The virus writes its code to the global template, "". Once the global template is infected, all documents used on the system will become infected.

Virus Characteristics

This is a polymorphic macro virus, affecting Microsoft Word97 (and higher) documents and templates. When an infected document is opened and the macros are allowed to run, the virus attempts to disable Word's virus warning, save normal template prompt, and confirm file conversion prompt. The TOOLS|MACRO and VIEW menus are hidden. When the hot keys ALT-F8 and ALT-F8 are pressed, the message "hahaNOT" is displayed. The following registry key value is created (the "PATCH.EXE" program referenced is not associated with this virus):

Run\PATCH="c:\windows\Patch.exe /pass:killfhc"

The macro also attempts to disable and delete anti-virus software. A side-effect of this attempt may be the deletion of files in the root directory, including necessary, critical files.

If the minutes and the seconds are the same, the virus changes the screen resolution to 320x200 and sets mouse trails to 9.

If the hour and the day are the same, the virus attempts to append all files in "C:\" with the virus code. On September 7, the virus changes the system colors.

Use current engine and DAT files for detection and removal.

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.

AVERT Recommended Updates:

* Office 2000 updates

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


PC Infected? Get Expert Help

Virus Removal Service

Connect to one of our Security Experts by phone. Have your PC fixed remotely - while you watch!