Backdoor.Hale

NOTE: Symantec Security Response has received several variants of this backdoor package. Two such variants are described below, but other variants could appear that use different filenames and directories.

Version 1

The installer for this version is a self-extracting CAB archive. It may be found in the system folder as a file named Nx.exe.

When Backdoor.Hale is executed, it performs the following actions:

1. Creates the folder, C:\Winnt\System32\Qossrv.
   
   NOTE: This path is hard-coded and is used for all the operating systems.
   
   
2. Copies the following files into the above directory:
   
   • Aysshell.exe: A legitimate "At Your Service" utility from Prism Microsystems.
   • Cdir.txt: A harmless text file.
   • Csrss.exe: a Backdoor Trojan Horse detected as Backdoor.Padmin.
   • Firedaemon.exe: A legitimate FireDaemon utility (used to start service processes).
   • Libeay32.dll: A legitimate .dll file.
   • Mswinsck.ocx: A legitimate .ocx file.
   • Pskill.exe: A legitimate utility used to kill processes.
   • Secure.exe: Detected as Backdoor.Hale.
   • Servuperfcount.dll: A legitimate .dll file that Winmgnt.exe uses.
   • Setup.bat: A batch file detected as Backdoor.Hale.
   • Setup.pif: A harmless .pif file.
   • Ssleay.dll: A legitimate .dll file.
   • Winmgnt.exe: a Serv-U FTP server.
   • Winexplorer.dll: This is not a .dll, but a configuration file for the FTP server.
   • Wget.exe: A legitimate program to fetch files using HTTP.
   • "- V1.0D (Haley) -": A 0-byte file.
     
     
3. Adds the value:
   
   "NTDLM" = "c:\winnt\system32\qossrv\csrss.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
   
4. Adds the value:
   
   "port" = "6351"
   
   to the registry key:
   
   HKEY_CURRENT_USER\Software\VB and VBA Program Settings\pAdmin\Settings
   
   to open port 6351.
   
   
5. Removes the network shares listed on the computer.
   
   
6. Uses Asyshell.exe to start the following services:
   
   • NTF (Winmgnt.exe)
   • NTS (Secure.exe)
   • NTP (Csrss.exe)
     
     NOTE: Some variants may use different names for the services.
     
     
7. Opens ports 5555 and 48522 using Winmgnt.exe.

Version 2:

This variant is not known to use a self-contained installer, like Nx.exe in the previous version.

The infection is similar to Version 1, except the files are copied into these directories:

C:\Winnt\System32\dhcp:

• Csrsslsrms.dll: A text file, not a dll.
• Explorer.exe: A Serv-U FTP server, detected as Backdoor.Hale.
• Fport.exe: A utility used to list the processes with open network connections.
• Igfxtray.exe: Detected as Backdoor.Trojan.
• Nc.exe: A network utility.
• Ntlmconf.dll: A text file, not a dll.
• Pskill.exe: A utility used to kill processes.
• Pslist.exe: A utility used to list processes.
• Rar.exe: An archive utility.
• Reg.exe: A utility used to edit the registry.
• Rmns.exe: Detected as Backdoor.Hale.
• Service.exe: A utility used to start the service processes.
• SystemUptimeLog.ocx: A log file.
• Tar.exe: An archive utility.
• Tlister.exe: A utility used to list processes.
• Wget.exe: A utility used to fetch files using HTTP.
• WinExplorer.dll: A configuration file, not a dll.

C:\Winnt\System32\restore:

• Csrss.exe: Detected as Backdoor.Padmin.
• MSWINSCK.OCX: A legitimate system file.
• Pskill.exe: A utility used to kill processes.
• Reg.exe: A utility used to edit the registry.
• Service.exe: A utility used to start the service processes.
• Binary.gif
• Compressed.gif
• Del.gif
• Dir.gif
• Folder.open.gif
• Image1.gif
• Image2.gif
• Movie.gif
• Pdf.gif
• Script.gif
• Sound2.gif
• Tar.gif
• Text.gif
• Thumbs.db

There have also been reports of variants that install files in C:\Winnt\System32\config or C:\Winnt\System32\home; and other folder and file names may be used in the future.

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