WM.Demon

SUMMARY

WM.Demon is the first semi-polymorphic macro virus to be found in the wild. This macro virus uses random macro names (thus semi-polymorphic). This macro virus does not have any malicious payload. There were reports of WM.Demon infections from Europe in the middle of 1997.

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Payload Trigger: Selected text is "Dark Master calling" when doc is closed.
• Payload: Displays message

Distribution

• Distribution Level: Low
• Target of Infection: Microsoft Word 6/95 document

TECHNICAL DETAILS

WM.Demon has three macros in document and template. In document, the macros are named AUTOOPEN and two randomly named macros. In global template (NORMAL.DOT), the macros are named AUTOCLOSE and two randomly named macros.

This macro virus infects global template upon opening an infected document. It infects other documents when the document is being closed.

Payload

While closing an infected document, the virus checks the currently selected text. If the currently selected text is Dark Master calling, the virus displays a message box titled Microsoft WinWord DEMON with this message:

WINWORD HIDDEN DEMON
is happy to see his MASTER!!!
GREAT DAY !!!
This file is infected as # XYZXYZ

XYZXYZ is formed from random characters.

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

Norton AntiVirus users can protect themselves from this virus by downloading the current virus definitions either through LiveUpdate or from the Download Virus Definition Updates page.