W97M.Verlor

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Discovered: December 06, 1999
Updated: February 13, 2007 11:45:59 AM
Also Known As: W97M.Overlord
Type: Macro


W97M.Overlord is a macro virus, which infects Microsoft Word97 (including SR-1) and Word2000 documents. This virus places its code in a macro module named Module . The virus has stealth capabilities so, when opening the Visual Basic Editor or selecting Tools | Macro , the virus will remove all infectious code from open documents and the NORMAL.DOT and then will re-infect them at a later time.

The virus may also insert these files into your Windows directory: OVERLORD.B.VBS, OVERLORD.B.DLL, TEMPAD.DLL, and TEMPNT.DLL.

OVERLORD.B.DLL, TEMPAD.DLL, and TEMPNT.DLL cannot cause any viral infection. These files should be deleted.

The virus may also add the registry key:


    HKLM\software\RegisteredOwner = "the Overlord"

and may modify the WIN.INI, adding the line:

    run = <Windows directory>\overlord.b.vbs

This virus has no other payload.




5/15/2003 7:30:47 AM -- John Bollinger -- <Outsourcer> -- New Suggestion
Customer had Protector Plus virus software that supposedly found and removed virus. Initially we searched for "overlord" and there was nothing. We checked the registry and win.ini and there was nothing. Thinking through the process the virus takes, I opened Word, then tools and started Visual Basic Editor and closed, then closed Word. I then searched for "overlord" and found both OVERLORD.B.VBS and OVERLORD.B.DLL and deleted both. The entry RegisteredOwner = "the Overlord" was not a "KEY" under KLM\software\, but was an entry on the right hand side below Default Value - we deleted. Then, we checked win.ini and the run= c:\Windows\overlord.b.vbs was there - deleted that line too. We then looked in c:\himem.sys (not to be confused with himem.sys in c:\windows) - all it contained was references to .doc files - we deleted file and rebooted. We repeated the steps again (IE open Word and VB and closed - searched for overlord and it was not found, nothing in reg and nothing in win.ini.

So apparently the virus was repaired in the Word files infected, but the macro still existed. So regardless, it might be a good idea to go through the steps of opening VB and then searching for "overlord" to see if macro still is active.

Since the macro stealths itself and removes itself when you open VB, and doesn't re-create itself until you re-start Windows, you can remove the macro/virus this way. Follow up by running a virus scan with current defs.


Antivirus Protection Dates

  • Initial Rapid Release version December 06, 1999
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version December 06, 1999
  • Latest Daily Certified version August 09, 2016 revision 001

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Eric Chien

Discovered: December 06, 1999
Updated: February 13, 2007 11:45:59 AM
Also Known As: W97M.Overlord
Type: Macro


When opening documents, the virus appends the name of the document to the file C:\HIMEM.SYS . This allows the virus to keep track if opened documents were not infected so they can be infected at a later time.

When closing documents, the virus infection routine is activated. The virus first checks if the files TEMPAD.DLL or TEMPNT.DLL exist in the Windows directory. These are temporary files created by the virus for its infection routine. If they exist, the files are deleted.

The virus then turns off the macro virus protection feature.

Next, the virus infects the NORMAL.DOT and active documents. In the process, the virus creates the temporary files TEMPAD.DLL and TEMPNT.DLL. These temporary files cannot cause any viral infection.

Finally, the virus checks if the newly infected document filename exists in the file C:\HIMEM.SYS. If the filename exists, the line is removed signifying successful infection.

The virus also contains stealth features. If a user opens the Visual Basic Editor in attempt to view the macrocode, the virus calls a stealth routine. The stealth routine first adds the registry key:


    HKLM/Software\registeredOwner = "the Overlord"

Then, the virus opens the WIN.INI file and adds the line:

    run = <Windows directory>\overlord.b.vbs

Next, the virus inserts the file OVERLORD.B.VBS that contains viral code. The virus also creates a file named OVERLORD.B.DLL. This file is a plain text file and cannot cause any viral infection.

Finally, the actual stealth routine begins. The virus removes all the viral code in any open documents and the NORMAL.DOT, and the Visual Basic Editor is displayed. However, since the virus removed all the virus code, one may be fooled into believing they are not infected.

The VBS file that is inserted into the system then performs a re-infection when the computer is restarted. The VBS file re-infects the NORMAL.DOT and any files, which were left uninfected when opening the Visual Basic Editor. The C:\HIMEM.SYS file is used to determine which files need to be re-infected.

Also, when selecting the Tools | Macro menu, the virus removes all the viral code from the NORMAL.DOT and any open documents. After finishing with the Tools | Macro menu, the virus re-infects the NORMAL.DOT and open documents. This may lead one to believe they are not infected.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Eric Chien

Discovered: December 06, 1999
Updated: February 13, 2007 11:45:59 AM
Also Known As: W97M.Overlord
Type: Macro


The registry key:


    HKLM/Software\registeredOwner = "the Overlord"

should be removed or corrected.

The line:


    run = \overlord.b.vbs

should be removed from the WIN.INI file.

The virus turns off the macro virus protection feature of Word97. This can be enabled by selecting Tools | Options | General | Macro Virus Protection.

Any temporary files including OVERLORD.B.DLL, TEMPAD.DLL, and TEMPNT.DLL in the Windows directory may be deleted.

The infectious file OVERLORD.B.VBS should be deleted.

Writeup By: Eric Chien