W97M.StasOne

SUMMARY

This is a Microsoft Word metamorphic macro virus that spreads by infecting Microsoft Word documents and the global template, Normal.dot.

Protection

• Virus Definitions (Intelligent Updater) March 15, 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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Metamorphic viruses use a permutated virus body. The virus engine of a metamorphic virus can recompile itself into a new form. Therefore, the code of the virus is different from generation to generation.

When replicates, the virus tries to retrieve a file from the Web site http: //www.stas.net/2/one/one.txt.

This file stores the latest version of the macro virus. If it is found, then the virus updates itself. Next, it generates a random number, which is used to encode itself. This provides the metamorphic nature of the virus.

Other than replication, W97M.StasOne virus does not contain a malicious payload.

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:

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