W32.Bajar.Worm.Int

SUMMARY

W32.Bajar.Worm.Int copies and runs a .vbs file and attempts to mass-mail itself to all contacts in the Microsoft Outlook Address Book, but it fails to do so due to a programming bug.

Protection

• Virus Definitions (LiveUpdate™ Weekly) July 3, 2002
• Virus Definitions (Intelligent Updater) June 27, 2002

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

When W32.Bajar.Worm.Int runs, it does the following:

It creates the C:System.dll.vbs file and then executes it.

When the file runs, it displays this message:



It then attempts to copy itself to the following locations:

• C:WindowsSystemAnti-Virus.vbs
• C:WindowsSystemNorton.exe
• C:WindowsSystemFonts.chm
• C:WindowsSystemonavirus.html
• C:WindowsSystemHoko.exe
• C:WindowsSystemNeodrako.exe
• C:WindowsSystemNemesixx.exe
• C:WindowsSystemRazor.exe
• C:WindowsSystemEgrone.exe
• C:WindowsSystemRun.exe
• C:WindowsSystemNERFIX.vbs
• C:WindowsSystemRegedit.exe
• C:WindowsSystemMtv.exe
• C:WindowsSystemSuck.exe
• C:WindowsSystemGroup.exe
• C:WindowsSystemirkov.exe
• C:WindowsSystemRegedit.exe
• C:WindowsSystemFonts.exe
• C:WindowsSystemXpload.exe
• C:WindowsSystemMp3.vbs
• C:WindowsSystemMp3.exe

Next, the worm attempts to mass-mail itself to all contacts in the Windows Address Book. This fails due to a bug in the code. If it were successful, the email would have the following characteristics:

Subject: Nuevo programa para bajar musica gratis
Message: con este programa vas a poder bajar cualquier tipo de musica las mejores canciones
Attachment: There is no message attachment due to a bug in the worm.

To avoid sending itself again, the worm adds the value

mp3_sent yea

to the registry key

HKEY_CURRENT_USERSoftware

It then adds the value

mp3 C:windowssystemmp3.vbs

to the registry key

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun

so that the worm runs each time that you start Windows.

The .vbs script also deletes the file C:WindowsRundll.exe.

Finally, after executing the dropped .vbs script, the Portable Executable (PE) part of the worm deletes the following files:

• C:WindowsSystemVshield.vxd
• C:Autoexec.bat
• C:WindowsRegedit.exe
• C:WindowsRegedit.com

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. Update the virus definitions, run a full system scan, and delete all files that Norton AntiVirus (NAV) detects as W32.Bajar.Worm.Int.
2. Restore overwritten or deleted files from clean backups.
3. Delete the value
   
   mp3  C:windowssystemmp3.vbsexplorer
   
   from the registry key
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   

For details on how to do this, read the following instructions.

To scan with Norton AntiVirus and delete the infected files:

1. Obtain the most recent virus definitions. There are two ways to do this:
   • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
   • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
     
     Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.
     
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files.
   • NAV Consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • NAV Enterprise products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
3. Run a full system scan.
4. Delete all files that NAV detects as W32.Bajar.Worm.Int.
5. Replace deleted files from a clean backup, or reinstall them.
   
   NOTE: If the worm deleted Autoexec.bat, Rundll.exe (Windows 95/98/Me only), or Regedit.exe, you must restore them from a clean backup or reinstall them before you can continue.

To remove the value from the registry:

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

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:
   
   mp3  C:windowssystemmp3.vbsexplorer
   
4. In the right pane, delete the following value:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
5. Click Registry, and click Exit