Backdoor.Asylum

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Discovered: May 02, 2000
Updated: February 13, 2007 11:51:00 AM
Type: Trojan Horse


This Trojan horse has no visual indicators that the computer has been infected. When executed, the Trojan modifies the system to enable itself to run at startup. You will notice a serious degradation of performance because the Trojan uses most of the system's resources.

Antivirus Protection Dates

  • Initial Rapid Release version May 05, 2000
  • Latest Rapid Release version March 23, 2017 revision 037
  • Initial Daily Certified version May 05, 2000
  • Latest Daily Certified version March 23, 2017 revision 041

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Brian Ewell

Discovered: May 02, 2000
Updated: February 13, 2007 11:51:00 AM
Type: Trojan Horse


Backdoor.Asylum opens a large number of ports for listening. It will attempt to send an email notification, which contains information about your system, to the Trojan's creator.
The Trojan employs three different methods to enable itself at startup:

  • It adds the line C:\Windows\Wincmp32.exe to the Load= and Run= lines of the Win.ini file.
  • It adds Wincmp32.exe to the Shell=explorer.exe line of the System.ini file.
  • It creates the value SystemAdministration and sets it equal to Wincmp32.exe in the following registry keys:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

NOTE: At least one case has been reported in which the dropped file, and the references to it, was Winupd32.exe.

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.

Writeup By: Brian Ewell

Discovered: May 02, 2000
Updated: February 13, 2007 11:51:00 AM
Type: Trojan Horse


To remove this Trojan:

  1. Restart the computer in MS-DOS mode, and then delete the C:\Windows\Wincmp32.exe file.
  2. Restart the computer in Safe Mode.
  3. Use the System Editor (Sysedit.exe) to edit the Win.in and System.ini files. Remove any references to Wincmp32.exe (or to Winupd32.exe).
  4. Remove the registry entries made by the Trojan:

    CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.
    1. Click Start, and click Run. The Run dialog box appears.
    2. Type regedit and then click OK. The Registry Editor opens.
    3. Navigate to the following subkey:

      HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    4. In the right pane, delete the value:

      SystemAdministration Wincmp32.exe (Or Winupd32.exe.)

      NOTE: Other file names have been reported. In any case, delete the SystemAdministration value.
    5. Repeat steps 3 and 4 for the registry key:

      HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
  5. Restart the computer.


Writeup By: Brian Ewell