W97M.Lateni.A

SUMMARY

This is a macro virus that infects Microsoft Word documents. It adds the comment "Colgate.... badnews for a bad world" to the beginning of the Normal.dot template. The virus uses this comment to prevent multiple infections. The virus also contains the comment "Using your computer L8@nite is bad for you." If the Normal.dot template is open at 11:00 P.M., the payload program deletes several system files. This can cause the computer to become unusable.

Protection

• Virus Definitions (Intelligent Updater) January 5, 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: Medium
• Payload Trigger: When the hour of the day is 23.
• Payload: This virus deletes several systemfiles.
• Deletes Files: msdos.sys, io.sys, command.com and autoexec.bat

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When this virus is executed on a computer for the first time, it tries to hide its malicious actions. It first disables the macro virus protection in Microsoft Word. As a result, Word will no longer prompt you for permission to run macros, but will instead run them automatically. The virus then disables the macro toolbar and modifies various options within Microsoft Word.

The virus checks the second line of the Normal.dot template for the following comment:

Colgate.... badnews for a bad world.

If this text is found, the virus does not attempt to infect the Normal.dot template. If the comment is not found, the virus will export itself as C:Colgate.tmp, import itself into the Normal.dot template, and then remove the temporary C:Colgate.tmp file. It then performs the same test on the active document.

The third line of the Normal.dot template reads as follows:

Using your computer L8@nite is bad for you.

This is most probably added because of the payload that this virus contains. At 11:00 P.M. the virus will delete the following system files:

• C:Autoexec.bat
• C:Io.sys
• C:Msdos.sys
• C:Command.com

If the payload is executed, the computer will not work on reboot, and the deleted files will have to be replaced.

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 that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan. Make sure that NAV is set to scan all files.
3. If any files are found to be infected with W97M.Lateni.A, choose Repair.

If the payload was executed, you must replace the following files:

• C:Autoexec.bat
• C:Io.sys
• C:Msdos.sys
• C:Command.com