W97M/Ethan.a

This page shows details and results of our analysis on the malware W97M/Ethan.a

Download Current DAT: 6712

Threat Detail

Malware Type: Virus

Malware Sub-type: Macro

Discovery Date: 1999-01-21

Next Steps:

Overview
Characteristics
Symptoms
Method of Infection
Removal
Variants

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

4010 (1999-01-27)

Updated DAT

4813 (2006-07-24)

Minimum Engine

5.1.00

File Length

Description Added

1999-03-23

Description Modified

2002-11-22

Malware Proliferation

Characteristics

W97M/Ethan.a is a Word97 Macro Virus. It is a fast moving infector and reported to numerous AVERT Labs around the globe. Infection takes place when an infected Word document is closed, allowing the virus to propagate itself to normal.dot template.

W97M/Ethan.A is a parasitic class module infector, which consists of one macro, and is approximately 50 lines of code in length. It infects documents and templates using an algorithm to input data, from a source file
c:\ethan.___
to the host document. This source file is exported VBA code of the virus.

Viruses using class module infection method transfer the virus code to the "ThisDocument" container. This virus prepends its code and infects all documents accessed.

There is a 3-in-10 chance that this virus will modify the document properties of infected files:

Title = "Ethan Frome"
Author = "EW/LN/CB"

These properties will have to be changed back manually after the virus has been removed.

Ethan has one additional characteristic in that if it detects the "class.sys" file (created by the W97M/Class virus infection) on the machine it will delete it.

Symptoms

Existence of file "ethan.___" as mentioned above, changes to document properties as mentioned above.

Method of Infection

Opening infected documents will directly infect the local Word environment and any document used thereafter.

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

W97M/Ethan.eo