Backdoor.IRC.Flood.G

1. Creates the following files in the C:\Winnt\System32 folder:
   • Explore.dat: This file is not viral itself, and Symantec antivirus products do not detect it as such.
   • Explore.exe: This file will install and launch Explorer.exe, as well as modify the registry. It is detected as a Trojan Horse.
   • Explorer.exe: This is an IRC client that will connect to a server on port 6667.
   • Iiscached.dll: This is a malicious IRC script. It can send the file, Isa.exe, using IRC.
   • Isa.exe: A collection of files.
   • Libmodll.exe: Process Viewer utility. It can be used maliciously. This file is not viral itself, and Symantec antivirus products do not detect it as such.
   • Network.dll: This file is a list of user names. It is not viral itself, and Symantec antivirus products do not detect it as such.
   • Navd.dbx: This file is a list of user names. It is not viral itself, and Symantec antivirus products do not detect it as such.
   • Nttest.exe: Utility to remove administrator shares.
   • Psexec.exe: This file is not viral itself, and Symantec antivirus products do not detect it as such.
   • Rcfg.ini: This is a malicious IRC script.
   • Secud.bat: Nuisance batch script.
   • Rundll33.exe: This is a dropper of the rootkit package.
   • Tftp8676: Clean configuration file.
   • W32.driver.bat: This batch file will attempt to launch the IRC client over the network shares.
   • W32.exe: Hide window utility. It is not viral itself, and Symantec antivirus products do not detect it as such.
     
     
2. Adds the value:
   
   "Explore" = "C:\Winnt\system32\Explorer.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
   so that the Trojan runs when you start Windows.
   
   
3. Attempts to connect to an IRC server on port 6667. Once connected, the Trojan will await commands from its creator.
   
   
4. Attempts to remotely launch Rundll33.exe using network shares. The process is launched by using Psexec.exe.
   
   

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   Note: Psexec.exe is a legitimate tool named PsExec from sysinternals, and therefore Norton AntiVirus will not detect the process.

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5. Before the process is launched, the Isa.exe file will be copied to the remote computer.
   
   
6. If Isa.exe is executed, it creates the following files in the C:\Winnt\System32\Microsoft\Crypto\Isa folder:
   • BugSlayUtil.dll: Clean DLL.
   • Cygwin1.dll: Clean DLL.
   • Firedaemon.exe: Utility used to install the processes as a service. It is not viral itself, and Symantec antivirus products do not detect it as such.
   • In: Clean text file.
   • Kill.exe: Utility used to kill processes.
   • Libeay32.dll: DLL used to perform cyptography.
   • Libxml2.dll: Clean DLL.
   • Nttest.exe: Utility to remove administrator shares.
   • Psexec.exe: It is not viral itself, and Symantec antivirus products do not detect it as such.
   • Reset: Zero-byte file.
   • Rundil.exe: Fileserver for IRC.
   • ServuDaemon.ini: Malicious FTP configuration file.
   • Ssleay32.dll: Clean DLL.
   • Svhost.exe: FTP client. It is not viral itself, and Symantec antivirus products do not detect it as such.
   • Tar.exe: Clean compression utility. It is not viral itself, and Symantec antivirus products do not detect it as such.
   • Temp.txt: This is a malicious IRC script.
   • Tzolibr.dll: Clean DLL.
   • Win32gnu.dll: Clean DLL.
   • Xd.bat: Malicious batch script that installs RundIl.exe and Svhost.exe as services.

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.