W97M/Suppl

This is combination Word97 class module virus which contains an embedded EXE file which is an internet worm with a trojan payload. Itis received in a file attachment named "SUPPL.DOC" in email messages. It functions similar to W32/Ska in that the local file WSOCK32.DLL is replaced with a rogue copy self contained within the document as an embedded object. The new WSOCK32.DLL contains instructions to attach the file "SUPPL.DOC" to email messages using SMTP protocol. This virus was first discovered by "Virus Patrol", a newsgroup scanning program in use by Network Associates Inc, cross-posted in several sex related newsgroups including "alt.sex.phone".

"SUPPL.DOC" has macro code which uses advanced technique to make use of routines found in the DLL files LZ32.DLL and KERNEL32.DLL. When the document is opened, if macro warning is enabled, a warning appears. If the macros are enabled the code within the macro performs the following operations-

* determines the Windows directory using API function
* writes 4 files to the Windows directory
WININIT.INI ( 143 bytes)
DLL.LZH ( 6,712 bytes)
DLL.TMP (16,384 bytes)
ANTHRAX.INI(38,968 bytes)
* transfers itself to documents by embedded file objects during the system event of opening a document

The file DLL.TMP is a replacement WSOCK32.DLL file. The contents of the WININIT.INI file instruct the operating system to replace the current WSOCK32.DLL file by first renaming it to WSOCK33.DLL, then renaming DLL.TMP to WSOCK32.DLL. The file DLL.LZH is removed. Windows uses the WININIT.INI file at boot time to perform these actions.

Every email message which is sent via SMTP e-mail client will have the attachment "SUPPL.DOC". The string "Anthrax" is within the internet worm however this name was not chosen for this virus due to it already being known by this name as a rather old DOS virus.

Payload Approximately 163 hours (6.79 days) after initially infecting the local machine,the trojanized WSOCK32.DLL will seekall files within all local drives (all mapped and physical drives) with the following extension andnull them similar to W32/ExploreZip: .doc, .xls, .txt, .rtf, .dbf, .zip, .arj, .rar, *.*

Macro warning if opening infecteddocument, increase in size toglobal template, confirmation of changes to NORMAL.DOT.

Opening infected documents will infect global template normal.dot.

Removal Files not repaired should be replaced with back-up copy. If the trojan payload has occurred, nulled files can possibly be recovered using an undelete recovery software program. To recover the WSOCK32.DLL file, reboot to MS-DOS mode, switch directories to the Windows\system folder and copy WSOCK33.DLL as WSOCK32.DLL, then reboot.

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.