VBS.Breberka.A@mm

SUMMARY

VBS.Breberka.A@mm is an encrypted .vbe worm that sends itself as an attachment to all users in all MAPI address books. The message is:

Subject: IQ Test!!!
Message: r u stupid? [Y/N] ;)))
Attachment: Breberka.txt<10 blank spaces>.vbe

It also attempts to connect to fixed and network drives in an effort to replicate.

Protection

• Virus Definitions (Intelligent Updater) April 3, 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
• Large Scale E-mailing: All MAPI address lists
• Modifies Files: autoexec.bat

Distribution

• Distribution Level: High
• Subject of Email: IQ Test!!!
• Name of Attachment: Breberka.txt[10 spaces].vbe
• Size of Attachment: 2,655 bytes

TECHNICAL DETAILS

When executed, VBS.Breberka.A@mm does the following:

1. This worm checks for the existence of the following registry key before attempting to activate its payloads:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionBreberka
   
   with a value of:
   
   ...by gl
   
   
2. If this registry key does not exist, the worm creates a copy of itself in the current Windows folder as Winhelp.vbe and in the current Windows temporary folder as Breberka.txt[10 spaces].vbe.
3. It then mails to all entries in all MAPI address books and creates the Breberka registry key to prevent future activation.
4. The value:
   
   SysHelp / StartUp     C:Windowswinhelp.vbe
   
   is added to the registry key
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   This ensures that the worm is run when Windows starts.
5. Next, the worm attempts to connect to all fixed and network drives, and creates two files in the root folders of these drives:
   • A 16-byte file named Dropper.com
   • A copy of the worm named Breberka.txt<10 spaces>.vbe
6. Finally, the worm attempts to modify any file named Autoexec.bat that is found on any of the drives, so that Dropper.com is run when Windows starts.

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, delete files detected as VBS.Breberka.A@mm, and then remove the entries added to the registry.

To remove the worm:

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. Delete any files detected as VBS.Breberka.A@mm.

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 the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionBreberka
   
4. In the right pane, delete the following value:
   
   ...by gl
   
5. Navigate to the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
6. In the right pane, delete the following value:
   
   SysHelp / StartUp     C:Windowswinhelp.vbe
   
7. Click Registry, and click Exit to save the changes.