W32.Modnar.Worm@mm

SUMMARY

W32.Modnar.Worm@mm is a mass-mailing worm that appears to be written in C++. When executed, the worm extracts all of the email address from the Windows Address Book (WAB). The worm then emails a copy of itself to all of the extracted email addresses.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (Intelligent Updater) August 14, 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: Medium
• Name of Attachment: Random. It will always have the extension .doc.pif
• Size of Attachment: 33,280 bytes

TECHNICAL DETAILS

When executed, the worm W32.Modnar.Worm@mm creates a copy of itself in the same folder. The name of the file that it creates is random, but always has the extension .doc.pif. Some examples of file names are:

• Nbgmcknc.doc.pif
• Dhjgktjm.doc.pif
• Wsyrlmzu.doc.pif

It next attempts to send the copy to everyone in the Windows Address Book (WAB). However, the email routine requires an active MAPI session. Therefore, for the worm to send itself out you must be logged in to a MAPI-compliant email program, such as Microsoft Outlook.

The worm does not modify any files on the system, nor does it add or modify any registry keys. If the worm is executed a second time, it will create another copy of itself and attempt to email this copy to everyone in the WAB.

All samples that we have received have been packed with a known runtime compression program that is used for Portable Executable (PE) files. The size of the worm, when uncompressed, is approximately 180 KB.

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

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. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as W32.Modnar.Worm@mm.