VBS.Forgotten.A@mm

SUMMARY

VBS.Forgotten.A@mm is a Visual Basic Script worm. Like many other worms, it uses Microsoft Outlook, mIRC, and Pirch to spread itself. The worm does not spread as an attachment within Outlook but as an HTML-formatted email that requires the user to enable ActiveX to run its code. Any .vbs and .vbe files are overwritten with a copy of the worm.

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low
• Large Scale E-mailing: Sends one email as a BCC to all entries in Microsoft Outlook address lists.
• Modifies Files: Overwrites all .vbs and .vbe files with a copy of itself. Modifies System registry. Overwrites script.ini and events.ini if the appropriate software is installed.

Distribution

• Distribution Level: Low
• Subject of Email: RE: FINANCING
• Shared Drives: Overwrites .vbs and .vbe files on all mapped network drives or floppy drives in which a disk is present.

TECHNICAL DETAILS

When executed, the VBS.Forgotten.A@mm worm performs the following actions:

• Copies itself to the Windows System directory as vb1.com.vbs.
• Searches for the mIRC program directory. If present, the worm overwrites the Script.ini file to spread itself when connected to mIRC.
• Searches for the Pirch program directory. If present, the worm overwrites the Events.ini file to spread itself when connected to Pirch.
• Sends a single email message to each address list found in Outlook, with each address entry added as a BCC address.
• Searches for .vbs and .vbe files on mapped drives, shared drives, and floppy disk drives in which disks are present. Overwrites these files with a copy of itself.
• Adds the value vb1 to the registry key HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun to enable itself at startup.

The worm also keeps a record of its infection by creating the registry key HKEY_CURRENT_USERSoftware(ANSWER). In this key, it stores information after it attempts to mail itself using Outlook. It also records whether it has affected the mIRC or Pirch programs. These actions are marked by the values "mailed," "mirqued," and "pirched" being created and set to 1. This lets the worm perform a check for previous infections.

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 worm:

1. Run a full system scan, making sure that Norton AntiVirus is set to scan all files.
2. Delete any file detected as infected with VBS.Forgotten.A@mm. These files cannot be repaired, and must be restored from clean backup copies.
3. Using Registry Editor, select the following registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   vb1
   
5. Delete the following registry key:
   
   HKEY_CURRENT_USERSoftware(ANSWER)