Backdoor.Nibu.D

1. Copies itself as these files:
   • %System%\Load32.exe
   • %Startup%\Rundllw.exe
   • %Windir%\Dllreg.exe
   • %System%\Vxdmgr32.exe
     
     

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     Notes:
     • %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).
     • %Startup% is a variable. The worm locates the Windows startup folder and copies itself to that location. For example, this is C:\Windows\Start Menu\Programs\Startup (Windows 95/98/Me) or C:\Documents and Settings\<current user>\Start Menu\Programs\Startup (Windows NT/2000/XP).
     • %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
       

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2. Adds the value:
   
   "load32"="%System%\load32.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   so that the Trojan runs when you start Windows.
   
   
3. Creates and loads a .dll file to capture keystrokes. Known variants have used the following file names:
   • %Windir%\sock32.dll
   • %Windir%\sock55.dll
   • %Windir%\sock64.dll
     
     
4. May create the registry key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\SARS
   
   
5. Modifies the [windows] section of the Win.ini file (Windows 95/98/Me only) to:
   
   [windows]
   run=%Windir%\dllreg.exe
   
   
6. Modifies the [boot] section of the System.ini file (Windows 95/98/Me only) to:
   
   [boot]
   shell=explorer.exe %System%\vxdmgr32.exe
   
   so that the worm runs when you start Windows 95/98/Me.
   
   
7. Modifies the value data of:
   
   Shell
   
   in the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
   
   from:
   
   "explorer.exe"
   
   to:
   
   "explorer.exe %Windir%\system32\vxdmgr32.exe"
   
   so that the worm runs when you start Windows NT/2000/XP.
   
   
8. Looks for windows that have certain strings in the title bar. These strings vary, but may include the following:
   
   • @NetMan
   • westpac
   • money
   • pay
   • hsbc
   • bank
   • halifax
   • barclays
   • punk
   • banco
   • e-gold Account
   • Hong Leong
   • Yahoo! mail
   • SignOn
   • SignIn
   • credit report logon
   • Login
   • LogOn
     
     

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     Note: Typically, such windows would be Web browser windows displaying logon screens for financial services or email accounts.

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9. Captures keystrokes that are typed into windows with the above strings and stores them in a log file. This file may be named %Windir%\vxdload.txt or %Windir%\bank.log.
   
   
10. Launches a thread that monitors the Clipboard, saving any data that is found to a log file. This file may be named %Windir%\rundllx.sys.
    
    
11. If the logon page for Barclays bank is visited, the Trojan will attempt to create screenshots of specific parts of that page. The screenshots will be saved as %windir%\bank1.bmp and windir%\bank2.bmp.
    
    
12. Periodically checks the size of the files it uses for logging stolen information. When the files are a certain size, the log files will be emailed to a hard-coded email address, along with System information such as the IP address and operating system. The Trojan also attaches the previously mentioned screenshots.

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.