VBS.Pleh.A@mm

SUMMARY

VBS.Pleh.A@mm sends itself to email addresses in the Microsoft Outlook address book. It overwrites files on local and remote drives, including files with the extensions .mp3, .pwd, .exe, .mp2, .doc, .avi, .mpeg, or .htm. The contents of these files are replaced with the source code of the worm, destroying the original contents.

Protection

• Virus Definitions (LiveUpdate™ Weekly) March 27, 2001
• Virus Definitions (Intelligent Updater) March 27, 2001

Threat Assessment

Wild

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

Damage

• Damage Level: High
• Payload Trigger: On execution of email attachment
• Payload: Overwriting files, formating the C-Drive
• Large Scale E-mailing: Sends itself to all addresses in the Microsoft Outlook Address Book
• Modifies Files: Overwrites files with the following extensions: .mp3, .pwd, .exe, .mp2, .doc, .avi, .mpeg, or .htm. Modifies files: "C:AUTOEXEC.BAT" and "C:WINDOWSWin.Ini"
• Degrades Performance: Might clog the email server

Distribution

• Distribution Level: High
• Subject of Email: I hate you
• Name of Attachment: help.vbs
• Size of Attachment: 3,499 bytes
• Shared Drives: Overwrites files located on network drives
• Target of Infection: Overwrites files with the following extensions: .mp3, .pwd, .exe, .mp2, .doc, .avi, .mpeg, or .htm.

TECHNICAL DETAILS

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

1. It copies itself to the WindowsSystem folder as Kernel.vbs and to the Windows folder as Help.vbs.
2. For each drive, including network drives, the virus attempts to infect files that have .vbs and .vbe extensions. The worm also searches for files with the extensions .mp3, .pwd, .exe, .mp2, .doc, .avi, .mpeg, or .htm, and overwrites them with viral code.
   
   CAUTION: Do not attempt to run files that have been overwritten or renamed by this worm. If you do, the worm is executed again.
   
3. VBS.Pleh.A@mm uses MAPI calls to the Microsoft Outlook program and creates messages by going through all of the addresses in the Microsoft Outlook Address Book. The worm uses the Windows registry to keep track of those who have been sent email, so that each is sent only one message:
   
   Subject: I hate you
   
   Message: i think that you must see this file ,i insist.
   
   Attachment: help.vbs
   
4. It creates the WindowsLook Here folder.
5. It then creates a text file in the Look Here folder. This text file contains the following text:
   
   Hello!It so pity that i cant look at your face now,and do you know why ,because your machine was infected by Lynx[RAtm].Worm.Regards from Od.
   
6. The worm also searches for the Logos.sys file, and deletes it if found.
7. Next, it attempts to delete the folder C:WindowsÐàáî÷èé ñòîë.
8. VBS.Pleh.A@mm modifies the C:Autoexec.bat file in an attempt to format drive C the next time the computer is restarted.
9. It configures itself to run each time the computer restarts by adding the line
   
   run=C:Windowshelp.vbs
   
   to the C:WindowsWin.ini file.
   
10. It also adds the value
    
    help     C:WINDOWShelp.vbs
    
    to the registry key
    
    HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersion
    RunServices
    
11. Once the worm has been executed, it displays the message
    
    Read Youmustread.txt file:-)

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, remove the changes it made to the Autoexec.bat and Win.ini files, delete any files detected as VBS.Pleh.A@mm, and remove the registry value that it added.

CAUTION: Do not restart the computer until you remove the commands from the Autoexec.bat file.

To edit the Autoexec.bat and Win.ini files:

1. Click Start, and click Run. The Run dialog box appears.
2. Type sysedit and then click OK. The System Configuration Editor opens.
3. In the Autoexec.bat file, look for the following lines and delete them:
   
   @cls
   @Please wait it can take only few minuts
   @format C:
   
4. Click File, and click Save.
5. Click the C:WindowsWin.ini title bar.
6. Located and delete the line
   
   run=C:Windowshelp.vbs
   
7. Click File, and click Save.
8. Close the System Configuration Editor.

To remove the worm files:

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.Pleh.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_MACHINESoftwareMicrosoftWindowsCurrentVersion
   RunServices
   
4. In the right pane, delete the following value:
   
   help     C:WINDOWShelp.vbs
   
5. Click Registry, and click Exit to save the changes.

(Optional) Remove the folder
Using Windows Explorer, delete the C:WindowsLook Here folder.