Backdoor.IRC.Ratsou.B

The Trojan may be downloaded by Trojan.Downloader.Aphe from the Web site, http:/ /amateur.freegayspace.com.

When Trojan.Downloader.Aphe runs, it attempts to download a file to C:\Note.exe, which is detected as Backdoor.IRC.Ratsou.B, from the same Web site. Then, the Trojan executes C:\Note.exe.

When C:\Note.exe runs, it does the following:

1. Creates the folder, %Windir%\Debug\UserMode.
   
   NOTE: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
   
   
2. Creates the following files in the Windows installation folder:
   • Aim.txt, configuration information, clean.
   • Aim.dll, configuration information, clean.
   • Boot.exe, SysInternals Psexec.exe tool, clean.
   • C.dll, an IRC script file, detected as Backdoor.IRC.Ratsou.B.
   • Crazy.exe, a Denial of Service (DoS) Tool, detected as Hacktool.DoS.
   • Dr.exe, a Denial of Service Tool, detected as Hacktool.DoS.
   • Empavms.exe, a Hide Window utility, clean.
   • Flood.ocx, an mIRC script used to flood. Detected as Backdoor.IRC.Ratsou.B.
   • Ipservers.dll, list of IRC servers, clean.
   • Java.dll, an mIRC script that downloads and runs a proxy. Detected as Backdoor.IRC.Ratsou.B.
   • Lan.bat, a bat file that tries to locate machines with weak passwords. Detected as Backdoor.IRC.Ratsou.B.
   • LibParse.exe, a process viewer, clean.
   • Lsass.exe, hacked mIRC32 client, detected as Backdoor.IRC.Ratsou.B.
   • Miconfig.exe, a Denial of Service Tool, detected as Hacktool.DoS.
   • Moo.dll, clean legitimate dll, clean.
   • Msccl.dll, mIRC script used with AIM, detected as Backdoor.IRC.Ratsou.B.
   • Msconig.exe, legitimate proxy program, clean.
   • Newuser.bat, modifies current security settings, detected as Backdoor.IRC.Ratsou.B.
   • Nhtml.dll, legitimate dll, clean.
   • Ratsou.exe, downloads file from amateur.freegayspace.com to C:\Note.exe. Added as Trojan.Downloader.Aphe.
   • Regedit.dll, mIRC script to read registry, clean.
   • Remote.ini, mIRC script that configures all the malicious aliases. Detected as Backdoor.IRC.Ratsou.B.
   • Restart.exe, executable to restart Windows, clean.
   • Screen.dll, an mIRC script that performs malcious actions such as stealing the Half-Lif Key. Detected as Backdoor.IRC.Ratsou.B.
   • Sipg.ocx, an mIRC script used to join specific channels. Detected as Backdoor.IRC.Ratsou.B.
   • Start.ocx, an mIRC script that will scan for machines vulnerable to the IIS Traversal exploit and will copy itself to that machine. Detected as Backdoor.IRC.Ratsou.B.
   • Sysboot.dll, an mIRC script to hide the mIRC program. Detected as Backdoor.IRC.Ratsou.B.
   • Sysconfig.ocx, an mIRC script to find machines with weak passwords and to copy and run the Trojan on the remote machine. Detected as Backdoor.IRC.Ratsou.B.
   • Syste32.dll, an mIRC script to set the Run registry. Detected as Backdoor.IRC.Ratsou.B.
   • Temp, configuration file, clean.
   • Unicod_ready, file with server names, clean.
   • Users.dll, file with user names, clean.
   • Wincmd34.bat, batch file to locate machines with weak passwords. Detected as Backdoor.IRC.Ratsou.B.
   • Wind.dll, configuration file for mIRC32, clean.
     
     
3. The following files are also created:
   • %System%\Hid.exe, installs Explorer.dll and Iexplore.dll, detected as Backdoor.IRC.Ratsou.B.
   • %System%\Explorer.dll, a tool to hide processes, detected as Backdoor.IRC.Ratsou.B.
   • %System%\Iexplore.dll, a tool to hide processes.
     
     
4. Adds the values:
   
   "HID.EXE"="%System%\HID.EXE"
   "lsass"="%Windir%\Debug\UserMode\lsass.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
   so that this patched mIRC program runs when you restart Windows.
   
   
5. Hooks the IRC file extensions in HKEY_LOCAL_MACHIN\Software\Classes, which call %Windir%\Debug\UserMode\lsass.exe when chat files are opened.
   

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.

Summary