W97M.Strings.I

SUMMARY

This is a Microsoft Word macro virus that spreads by infecting Microsoft Word documents and the global template, Normal.dot. The virus attempts to decrease the security level of Microsoft Word 97, 2000, and XP.

NOTE: This virus was previously known as W97M.Tester.A.

Protection

• Virus Definitions (Intelligent Updater) July 18, 2001

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
• Compromises Security Settings: Decreases security level from 3 to 1.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When a document that is infected with W97M.Strings.I is opened, the macro virus replicates itself into active documents and the Normal.dot template. It may change the following Word options:

• When you open a document that contains a macro, the warning message no longer appears by default.
• The menu option that controls macro settings is disabled.

The virus also adds the following registry keys (if they do not exist) to decrease the security level of Microsoft Word:

HKEY_CURRENT_USERSoftware
MicrosoftOffice8.0WordSecurity

HKEY_CURRENT_USERSoftware
MicrosoftOffice9.0WordSecurity

HKEY_CURRENT_USERSoftware
MicrosoftOffice10.0WordSecurity

It sets the keys as follows:

ValueName: Level
Value: 1

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

To remove this virus, repair any files detected as W97M.Strings.I, and reverse the changes that it made to the registry.

To remove the virus:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
3. If any files are detected as infected by W97M.Strings.I , then click Repair.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to each of the following keys (if they exist):
   
   HKEY_CURRENT_USERSoftware
   MicrosoftOffice8.0WordSecurity
   
   HKEY_CURRENT_USERSoftware
   MicrosoftOffice9.0WordSecurity
   
   HKEY_CURRENT_USERSoftware
   MicrosoftOffice10.0WordSecurity
   
4. For each one that does exist, in the right pane, double-click the following value:
   
   Level
   
5. In the ValueData box, replace the 1 with 3, and then click OK.
6. Exit the Registry Editor.