Threat Explorer

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VBS.Melhack@mm

VBS.Melhack@mm

Discovered:
29 August 2002
Updated:
13 February 2007
Also Known As:
I-Worm.Melhack [AVP], VBS/VBSWG.at [McAfee], VBS/Kamil.B.Worm [CA]
Systems Affected:
Windows


VBS.Melhack@mm is a Visual Basic script worm that spreads by emailing itself to all the contacts in the Windows Address Book. It also does the following:
  • It creates registry values and keys that (among other things) cause the worm to run when you start Windows.
  • It visits a Web site and then downloads and runs the W32.Kamil Trojan.
  • It modifies the mIRC script file to send itself over IRC.
  • It creates several folders and files on the host computer.
  • It overwrites files on the computer with a copy of one of its components.





NOTE: Definitions dated prior to August 30, 2002 detect this as Bloodhound.VBS.4.

Antivirus Protection Dates

  • Initial Rapid Release version 30 August 2002
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 30 August 2002
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 04 September 2002
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

VBS.Melhack@mm may arrive as an email message with the following characteristics:

Subject: << Nur_Mohd_Kamil >>
Message body (Written in HTML):
Hello,

My name is <name of author>, I'm 19 years old. I would like to introduce my new transport called OsamaBinLaden Digital Transport.
I write this message cause I want to explorer in the whole world using Digital transport. So, where I arrive now?

By
<Name of author>

If ActiveX is disabled, then the only visible text will be

You need ActiveX enabled if you want to see this e-mail.Please open this message again and click accept ActiveX
Microsoft Outlook

VBS,Melhack is an encrypted worm that contains several blocks of encrypted code. Each block's functions are described separately here.

Block 1
  • In the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion

    block 1 creates or changes the Value Data of RegisteredOwner to OsamaBinLaden.
  • It adds these values:

    OsamaBinLaden  wscript.exe c:\Windows\System\OsamaBinLaden.vbs % (This path is hard-coded)
    Melhacker        C:\Melhacker.bat

    to the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    so that it runs each time that you start Windows.
  • It copies the worm to %system%\OsamaBinLaden.vbs

    NOTE: %system% is a variable. The worm locates the System folder and copies itself to that location. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

Block 2
Block 2 creates and executes a file named Kamil.exe in the current folder (most often the Temporary Internet Files folder). This is a copy of W32.Kamil.

Block 3
When block 3 runs, the script creates C:\Melhacker.bat and executes it. The batch file performs the following actions:
  • It checks for the existence of C:\Melhacker.bat. If this file does not exist, the batch file copies itself to C:\Melhacker.bat then creates these empty folders:
    • C:\Windows\VBS.Kamil
    • C:\Windows\W32.Kamil
    • C:\Windows\W32.Blebla.J.Worm
    • C:\Windows\W32.Cbomb
    • C:\Windows\BAT.Melhacker Will Attack Your Computer
    • C:\Windows\Suck
    • C:\Windows\F*Ck
    • C:\Windows\Kill
    • C:\Windows\MURder
    • C:\Windows\Xtrap
    • C:\Windows\G.W.Bush Will Be KILled
    • C:\Windows\No Peace In America
    • C:\Windows\No Peace In Israel
    • C:\Windows\Nuklear Waiting For You
    • C:\Windows\The Hacker Will Survive
  • It changes the command prompt to $P$SWindows2000, where $P represents the current path and $S represents a space (for example, C:\Windows\System Windows2000).
  • It copies itself over C:\Autoexec.bat and C:\Windows\Dosstart.bat.
  • It deletes all .zip files in the root of drive C.
  • It copies itself over:
    • All .com files in the root of drive C.
    • All .txt, .xls, .doc, .exe, .rtf, .cab, .com, .avi, .gif, .bmp, .jpg, .jpeg, .tif, and .bat files in the C:\mydocu~1 folder.
    • All .doc, .jpg, .gif, .bmp, .cpp, .mdb, .xls, .avi, .mp3, and .bat files in the C:\Windows\Desktop folder.
  • It uses Internet Explorer to download and execute Nur_Mohammad_Kamil.exe (W32.Kamil).
  • It tries to delete files that match the following criteria (* is used as a wildcard):
    • C:\Windows\Application Data\Identities\{161C80E0-1B99-11D4-9077-FD90FD02053A}\Microsoft\Outlook Express\*.dbx (Outlook Express mailboxes).
    • C:\Windows\Application Data\Microsoft\Address Book\Ankit.wab.
    • C:\Windows\*.pwl (Windows saved password files).
  • It copies itself to C:\Windows\Start Menu\Programs\StartUp\Melhacker.bat.
  • It prints a message from the author.

Block 4
Block 4 creates these registry values:

Mailed 1
Mirqued 1
Pirched 1

under the registry key

HKEY_LOCAL_MACHINE\Software\OsamaBinLaden

to let the worm know that it has delivered its payloads, even though the emailing has not yet been performed. The modifications to mIRC and Pirch actually do not take place until Block 5 is executed.

If the day is February 3, then VBS.Melhack@mm downloads and executes NMKamil.exe (yet another W32.Kamil) from an Internet site (melhacker.netfirms.com).

Block 4 then takes care of emailing the worm--with the previously mentioned subject and body--to the contacts in the Windows Address Book.

If NMKamil.exe does not exist in the %windir% folder, then block 4 changes the Internet Explorer home page to a URL that will download and execute that file. Otherwise, VBS.Melhack@mm changes the home page to 'about:blank'.

Block 5
Block 5 creates Script.ini or Events.ini for mIRC or pIRCed, respectively. As a result, when someone joins a channel that an infected computer is using, the worm is sent to that person.

Finally, block 5 iterates through all folders on local and mapped drives to copy the worm over all files that have the .vbs, .vbe, .gif, .jpg, .bmp, .avi, .mp3, .mpg, .zip, .cab, .mdb, .xls, .lnk, .doc, .txt, or .rtf extensions.

Other text and strings in the worm
VBS.Melhack@mm also contains the following strings:

17 August 2002, Saturday, Made in Malaysia
MelHacker ViRus VerSion 1.30
Melhacker, Inc. (c) Copyright 1995-2002. All Right Reserved.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

NOTES:
  • These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  • If the worm has run, numerous files on your computer may need to be restored. Please refer to the Technical Description section for complete details. If you are not sure how to do this, we suggest that you obtain the services of a qualified computer consultant.
  1. Update the virus definitions, run a full system scan, and delete all files that are detected as VBS.Melhack@mm.
  2. Delete the values

    OsamaBinLaden wscript.exe c:\Windows\System\OsamaBinLaden.vbs % (This path is hardcoded)
    Melhacker C:\Melhacker.bat

    from the registry key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  3. Reverse the other changes that the worm made to the registry.
For details on how to do this, read the following instructions.

To scan for 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 your Symantec antivirus program, and make sure that it is configured to scan all files.
  3. Run a full system scan.
  4. If any files are detected as infected with VBS.Melhack@mm, click Delete. Infected files other than the original worm files should be restored from a clean backup or reinstalled, as will other files that the worm deleted.

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 key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the values:

    OsamaBinLaden  wscript.exe c:\Windows\System\OsamaBinLaden.vbs %  (This path is hard-coded)
    Melhacker      C:\Melhacker.bat
  5. Navigate to the key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
  6. In the right pane, update the value

    RegisteredOwner

    by double-clicking it and re-entering the name of the registered owner of the copy of Windows that is installed on the computer.
  7. Exit the Registry Editor.


Writeup By: Atli Gudmundsson