W97M.Nono.A

This macro virus affects Microsoft Word 97 documents by adding a Visual Basic Application (VBA) module to the document. The name of the VBA module is the user's initial.

Type:	Virus
Infection Length:	one VBA Module

Wild Number of infections: 0 - 49 Number of sites: 0 - 2 Geographical distribution: Low Threat containment: Easy Removal: Easy

Threat Metrics Wild: Low Damage: Low Distribution: Low

Damage

• Payload Trigger: 30 minutes after the hour, such as 9:30 or 10:30
• Payload: FIRST: When opening an infected document on the 30th minute of the hour, the virus changes the Application Caption to "VicodinES /TNN /CB " and shows an animated text "VicodinES" that's ended with ":-) VicodinES ---" on the status bar. Then, it changes the Application Caption to "Microsoft Word Loves " where TheUserName is taken from the user name that is shown in Tools-Option-UserInformation. It also inserts the same string into the current position in the document. SECOND: While opening an infected document on the 30th minute of the hour of the 10th of the month, the virus does not display the animated status bar. Instead, it displays a message box "Hard.Poppy" with a message: "Run Animation?"

Distribution

• Target of infection: Microsoft Excel 97 documents

The virus does not add a new VBA module in Global Template (usually the file NORMAL.DOT) but adds its viral code into the "ThisDocument" module.

After infecting the Microsoft Word Global Template, NORMAL.DOT, the virus copies it into the Microsoft Word Startup directory (as set in Tools-Options-FileLocations). To copy the file, the virus creates a temporary batch file, "C:\FALSE.BAT" or "C:\TRUE.BAT".

While infecting a document or global template, this macro virus uses a temporary text file. The virus uses the user initial (as set in Tools-Options-UserInformation) for the file name. For example, if the user initial is set to "JS", it creates "C:\JS" temporary file.

This macro virus tries to be stealthy by "stealing" the following menu:

• Tools-Macro
• Tools-Macro-VisualBasicEditor

• Prompt to save Normal template
• Macro virus protection

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.

Norton AntiVirus users can protect themselves from this virus by downloading the current virus definitions.

Norton AntiVirus can detect and repair the duplicate copy of NORMAL.DOT in the Microsoft Word Startup directory. However, this file should be deleted.

Although the temporary text file

C:\<UserInitial>

(where UserInitial is taken from the initial shown in Tools-Options-UserInformation) is harmless, deleting it is recommended.

Although the files "C:\FALSE.BAT" and "C:\TRUE.BAT" are harmless, deleting them is recommended.

The disabled options can be restored from Tools-Option menu.

Write-up by: Raul Elnitiarta