WM.Concept

SUMMARY

WM.Concept is a virus that uses five macros to infect hosts and spread itself.

The macros are named:

• AAAZAO
• AAAZFS
• AutoOpen
• FileSaveAs
• PayLoad

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

Distribution

• Distribution Level: Low
• Target of Infection: Microsoft Word documents

TECHNICAL DETAILS

All of the macros are easily visible from the Macro command of the Tools pulldown menu within Microsoft Word. Upon infection, WM.Concept looks for the PayLoad and FileSaveAs macros. If it finds either macro, WM.Concept aborts infection. If it does not find either macro, WM.Concept begins the infection process.

The first stage of infection that users see is a dialog box displaying the number "1" and an OK button. Once users press the OK button, WM.Concept gains control. The virus replaces the Save As command in the File pulldown menu with its own command, which forces the user to save all documents as new templates. Without notice, WM.Concept takes the contents of the AAAZAO macro and places it in another macro, called AutoOpen, in the new templates, and copies the AAAZFS, AAAZAO, and PayLoad macros to the new file. The AutoOpen macro is automatically started each time a template is opened, allowing the virus to replicate in the new documents.

Other than the number "1" displayed during initial residency, WM.Concept displays no message. However, the Pay Load macro contains the following message:

That’s enough to prove my point

This is a variant of the original Concept virus. It is identical in nature and function, however it has been modified and translated to work with French language versions of Microsoft Word.

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.