Printer Friendly Page

Discovered: March 15, 2001
Updated: February 13, 2007 11:37:40 AM
Type: Trojan Horse

Backdoor.NTHack is a backdoor Trojan that steals passwords.

For additional information, read the Microsoft Knowledge Base article Error Message: STOP 0x00000001e KMODE_EXCEPTION_NOT_HANDLED in Win32k.sys , Article ID: Q294728.

Antivirus Protection Dates

  • Initial Rapid Release version March 15, 2001
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version March 15, 2001
  • Latest Daily Certified version August 09, 2016 revision 001

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

Writeup By: Cary Ng

Discovered: March 15, 2001
Updated: February 13, 2007 11:37:40 AM
Type: Trojan Horse

Backdoor.NTHack does the following:

  1. It first executes the DL.bat file. When DL.bat is executed, this batch file changes the current folder to \Inetpub\scripts and attempts to connect to a specific Web site using TFTP. Once connected, it attempts to download the DL.exe file.
  2. The batch file then checks to see if DL.exe has been downloaded. If it has, it starts this executable.
  3. DL.exe is a Visual Basic program packed with UPX. When this program is executed, it attempts to connect to the IP address using FTP and download 14 files (named 00.d, 01.d, 02.d, through 13.d).
  4. Once the files have been downloaded, DL.bat renames 00.D to Install.bat. It then removes the read-only attribute from the TFTP program and DL.exe, and attempts to delete these two files. Install.bat is then called for execution.
  5. When Install.bat is executed, it renames the other 13 files to the following:
    • 01.d -> Dir.txt
    • 02.d -> FireDaemon.exe
    • 03.d -> Login.txt
    • 04.d -> MMtask.exe
    • 05.d -> NewGina.dll
    • 06.d -> Reggina.exe
    • 07.d -> Regit.exe
    • 08.d -> Restrict.exe
    • 09.d -> Restsec.exe
    • 10.d -> Settings.reg
    • 11.d -> SUD.exe
    • 12.d -> Makeini.exe
    • 13.d -> SUD.ini

      Most of these programs are legitimate programs (such as a packed version of Regedit.exe), but the backdoor Trojan utilizes these for malicious purposes. These files are deleted after the Trojan has finished using them.
  6. A temporary file that is used as a log file for the administrator's passwords may also be created. Changed passwords are also captured in this file.


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: Cary Ng

Discovered: March 15, 2001
Updated: February 13, 2007 11:37:40 AM
Type: Trojan Horse

To remove this worm, delete any files detected as Backdoor.NTHack and delete the value NewGina from the registry key

KEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

NOTE: If the hard drive is configured for NTFS, to be able to delete or rename any of the infected files, you must add the group "Everyone" to each of the files, assign special access, and enable the full set of privileges. Then restart the computer to take ownership of the files and allow removal of the infected files.

To remove the worm:

  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and then run a full system scan, making sure that NAV is set to scan all files.
  3. Delete any files that are detected as Backdoor.NTHack.

To edit the registry:

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

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

  5. Navigate in turn to each of the following keys, and delete the value that is indicate for each one:

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\os2srv\parameters
    Value: firestarter  <path to sud.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\index\parameters\
    Value: firestarter  <path to remscan.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\index
    Value: image path <path to fire demon.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\eventlog\application\index
    Value: event message file <path to fire demon.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\eventlog\application\mmtask
    Value: event message file <path to fire demon.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\eventlog\application\os2srv
    Value: event message file <path to fire demon.exe>

    Key: HKEY_LOCAL_MACHINE\system\currentcontrolset\services\mmtask
    Value: image path <path to fire demon.exe>

    Key:  HKEY_LOCAL_MACHINE\system\currentcontrolset\services\os2srv
    Value: imagepath <path to fire demon.exe>
  6. Click Registry, and click Exit.

Writeup By: Cary Ng