Backdoor.Nibu.E

1. Copies itself as some of the following file names:
   
   • %System%\netda.exe
   • %Startup%\netdb.exe
   • %System%\netdc.exe
     
     Notes:
     • %System% is a variable. The Trojan 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 Trojan 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).
       
       
2. Creates some of the following files for logging purposes:
   
   • %Windir%\prntk.log
   • %Windir%\prntc.log
   • %Windir%\TEMP\feff35a0.htm
   • %Windir%\TEMP\fa4537ef.tmp
   • %Windir%\TEMP\fe43e701.htm
   • %Windir%\netdx.dat
     
     Note: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and creates files in that location.
     
     
3. Adds the value:
   
   "load32"="%System%\netda.exe..."
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   so that the Trojan runs every time Windows starts.
   
   
4. Creates and loads a .dll file to capture keystrokes. Known variants have used %Windir%\prntsvr.dll as the file name, which is detected as Keylogger.Trojan.
   
   
5. May create the registry keys:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\SARS
   HKEY_USERS\.DEFAULT\SOFTWARE\SARS
   
   
6. 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 %System%\netdc.exe"
   
   so that the Trojan runs when you start Windows NT/2000/XP.
   
   
7. Modifies %Windir%\system.ini file by changing the value:
   
   Shell="Explorer.exe"
   
   to:
   
   Shell="explorer.exe %System%\netdc.exe"
   
   so that the Trojan runs when you start Windows 95/98/Me.
   
   
8. Looks for windows that contain any of the following strings in the title bar:
   
   • gold
   • Storm
   • e-metal
   • WebMoney
   • http: //westsideuu.org/images/logger.php
   • WM Keeper
   • Keeper
   • Fethard
   • fethard
   • bull
   • Bull
   • mull
   • PayPal
   • Bank
   • bank
   • cash
   • ebay
   • ePass
   • iKobo
   • Fidelity
   • EcoCard
   • Ameritrade
   • Wasington
   • capital
   • Wells Fargo
   • E*TRADE
   • Keyword 1
   • Keyword 2
   • Keyword 3
   • Keyword 4
   • Keyword 5
     
     
     Note: Typically, such windows would be Web browser windows displaying logon screens for financial services or email accounts.
     
     
9. Captures the window title and keystrokes that are typed into windows with the above strings, and then stores them in one of the log files created in step 2. Other stolen information that may also be stored in this file include the IP address of the infected machine and system information, such as the operating system and Internet Explorer version. It may try to steal the FAR Manager and FTP Commander passwords and protected storage data.
   
   
10. Launches a thread that monitors the Clipboard, saving any data that is found to one of the log files created in step 2.
    
    
11. Periodically checks the size of the files it uses for logging stolen information. When the files reach a certain size, the stolen information will be copied into an email-formatted file using the Trojan's own built-in SMTP engine. The Trojan retrieves the details of the registered owner from the registry and uses these details in the file.
    
    The email-formatted file has the following characteristics:
    
    From: <registered owner> <address@yandex.ru>
    To: you
    
    
12. Writes an HTML file containing stolen data to one of the log files created in step 2.
    
    
13. Writes a raw MIME message containing stolen data to one of the log files created in step 2.
    
    
14. Listens on some of the following TCP ports for remote instructions.
    
    • 1001
    • 10000
    • 23955
      
      
15. Disables access to certain antivirus Web sites by adding the following lines to %System%\drivers\etc\hosts:
    

127.0.0.1  avp.com                          
127.0.0.1  ca.com                            
127.0.0.1  customer.symantec.com            
127.0.0.1  dispatch.mcafee.com              
127.0.0.1  download.mcafee.com              
127.0.0.1  f-secure.com                      
127.0.0.1  kaspersky.com                    
127.0.0.1  liveupdate.symantec.com          
127.0.0.1  liveupdate.symantecliveupdate.com
127.0.0.1  mast.mcafee.com                  
127.0.0.1  mcafee.com                        
127.0.0.1  my-etrust.com                    
127.0.0.1  nai.com                          
127.0.0.1  networkassociates.com            
127.0.0.1  rads.mcafee.com                  
127.0.0.1  secure.nai.com                    
127.0.0.1  securityresponse.symantec.com    
127.0.0.1  sophos.com                        
127.0.0.1  symantec.com                      
127.0.0.1  trendmicro.com                    
127.0.0.1  update.symantec.com              
127.0.0.1  updates.symantec.com              
127.0.0.1  us.mcafee.com                    
127.0.0.1  viruslist.com                    
127.0.0.1  www.avp.com                      
127.0.0.1  www.ca.com                        
127.0.0.1  www.f-secure.com                  
127.0.0.1  www.kaspersky.com                
127.0.0.1  www.mcafee.com                    
127.0.0.1  www.my-etrust.com                
127.0.0.1  www.nai.com                      
127.0.0.1  www.networkassociates.com        
127.0.0.1  www.sophos.com                    
127.0.0.1  www.symantec.com                  
127.0.0.1  www.trendmicro.com                
127.0.0.1  www.viruslist.com

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.