Threat Explorer

The Threat Explorer is a comprehensive resource consumers can turn to for daily, accurate, up-to-date information on the latest threats, risks and vulnerabilities.

VBS.Kidarcade.F

VBS.Kidarcade.F

Discovered:
13 June 2001
Updated:
13 February 2007

VBS.Kidarcade.F is a virus based on Visual Basic Script (VBS). It has been put into an HTML page, and is on at least one Web site. The virus installs a Backdoor Trojan that allows unauthorized access to the infected computer.

Antivirus Protection Dates

  • Initial Rapid Release version 13 June 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 13 June 2001
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

VBS.Kidarcade.F is both a Visual Basic Script and a JavaScript virus. It utilizes the Scriptlet.TypLib ActiveX control, which allows local files to be created or modified. Microsoft has released a patch that eliminates security vulnerabilities in Scriptlet.TypLib. The patch removes the "safe for scripting" marking, thereby causing Internet Explorer to request confirmation from the user before loading the control. The patch is available at:

http://www.microsoft.com/technet/ie/tools/scrpteye.asp

VBS.Kidarcade.F performs the following actions:
  1. If the security settings on the computer allow the scripts to run, then the HTML page will copy the file Welcome.hta to the \Windows\StartUp folder. This file is a malicious Visual Basic Script, which will be executed every time that Windows starts.
  2. When executed, the script drops the binary file 3ascii.bin. It then runs the DOS/Windows utility Debug.exe with the parameter "3ascii.bin" passed to it. 3ascii.bin is a binary file written in assembly language, and consists of the decoder and the encoded body of the Backdoor Trojan Cgibin.exe. Debug.exe reads the decoder instructions into memory and passes execution control to them. The decoder extracts the body of the Backdoor Trojan from 3ascii.bin and writes it as the Cgibin.exe file.
  3. The script then moves the Backdoor Trojan to the \Windows folder and runs it. The 3ascii.bin binary file is then deleted.
  4. To enable the Backdoor Trojan to run at startup, the script creates the value

    SysWin   <Windows>\cgibin.exe

    in the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\Run
  5. When executed, the Backdoor Trojan copies itself to the \Windows folder as Winasm32.exe. To enable itself to run at startup the Trojan creates the value

    RegistryKeyName1234567890  <Windows>\Winasm32.exe

    in the following registry keys

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\Run

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\RunServices
  6. Then the Backdoor Trojan sends the message "hey there, ive been committed" to the ICQ pager of the virus author. This tells the remote computer that the infected computer is ready for remote administration. It then starts to accept and perform the remote commands. The remote administration has full access to the file system of the infected computer. The Trojan permits the remote administrator to download or upload files from the remote computer, change the registry, and run commands and programs.
  7. To prevent Windows from displaying the default .hta file extension, the script next creates the value

    NeverShowExt

    in the registry key

    HKEY_CLASSES_ROOT\htafile

    and changes the value of

    HKEY_CLASSES_ROOT\htafile\DefaultIcon\

    to

    SHELL32.DLL,44
  8. The script then creates the Wininit.ini file in the \Windows folder and writes the following lines in the file:

    [rename]
    NUL= <path> \Welcome.hta


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.

To remove this Trojan:
  • Run Live update and then end all network connections, scan with Norton AntiVirus, and delete files detected as VBS.Kidarcade.F or Backdoor Trojan.
  • Remove the text in the Wininit.ini file that refers to \Welcome.hta.
  • Remove the text in the Win.ini file that refers to \Winasm32.exe.
  • Remove the changes that were made to the registry.

The following sections offer detailed instructions.

To scan with Norton AntiVirus:

  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Make sure you have no network connections (unplug the network card and disconnect your dial-up connection, if any).
  3. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  4. Delete any files detected as VBS.Kidarcade.F or Backdoor Trojan. If any files are detected as VBS.Kidarcade.F or Backdoor Trojan; then when the scan is finished, restart the computer and repeat the full system scan with NAV.

To edit the Wininit.ini file:
  1. Click Start, point to Find or Search, and click Files or Folders.
  2. Make sure that "Look in" is set to (C:) and that Include subfolders is checked.
  3. In the "Named" or "Search for..." box, type--or copy and paste--the following file name:

    wininit.ini
  4. Click Find Now or Search Now.
  5. Double-click the Wininit.ini file that was found in the \Windows folder. It opens in Notepad.
  6. Look for the line <path>\Welcome.hta, and delete it if it exists.
  7. Save the changes, and close Notepad.

To edit the Win.ini file:
  1. Click Start, point to Find or Search, and click Files or Folders.
  2. Make sure that "Look in" is set to (C:) and that Include subfolders is checked.
  3. In the "Named" or "Search for..." box, type--or copy and paste--the following file name:

    win.ini
  4. Click Find Now or Search Now.
  5. Double-click the Win.ini file that was found in the \Windows folder. It opens in Notepad.
  6. Look for the lines <path>\winasm32.exe and delete them if they exist.
  7. Save the changes, and close Notepad.

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 key

    HKEY_CLASSES_ROOT\htafile
  4. In the right pane, delete the value

    NeverShowExt
  5. Navigate to the key

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\Run
  6. In the right pane, delete the values

    RegistryKeyName1234567890
    SysWin
  7. Navigate to the key

    HKEY_LOCAL_MACHINE\Software\Microsoft\
    Windows\CurrentVersion\RunServices
  8. In the right pane, delete the value

    RegistryKeyName1234567890
  9. Close the Registry Editor.


Writeup By: Serghei Sevcenco