Backdoor.Assasin.F

Printer Friendly Page

Discovered: April 29, 2003
Updated: February 13, 2007 12:00:40 PM
Also Known As: Backdoor.Assasin.20 [KAV]
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP



Backdoor.Assasin.F, which is a variant of Backdoor.Assasin , gives a hacker unauthorized access to a compromised computer. The existence of the file Ide.exe is an indication of a possible infection.

This Trojan Horse is written in the Borland Delphi programming language and is compressed with UPX.

Antivirus Protection Dates

  • Initial Rapid Release version April 30, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version April 30, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date April 30, 2003

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

Writeup By: Robert X Wang

Discovered: April 29, 2003
Updated: February 13, 2007 12:00:40 PM
Also Known As: Backdoor.Assasin.20 [KAV]
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP


When Backdoor.Assasin.F runs, it does the following:

  1. Creates the folder, %System%\IDE, and copies itself to this location as Ide.exe.

    NOTE: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Creates the following files:
    • %Windir%\1.mzp
    • %System%\IDE\1.mzp
    • %System%\IDE\1\0.dll (Detected as Backdoor.Assasin)
    • %System%\IDE\Ide0.idx
    • %System%\IDE\Ide00.dll
    • %System%\IDE\Ide1.idx

      NOTE: The last three files (ide*.*) are not viral, and therefore, Symantec antivirus products do not detect them.

  3. Adds a value:

    IDE       %System%\IDE\ide.exe

    to the following registry keys:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
    RunServices

    so that the worm runs every time Windows starts.

  4. Runs one of the following programs:
    • Iexplore.exe
    • Explorer.exe
    • Notepad.exe

      and then injects itself into that process.

  5. Attempts to download files from two specified URLs.

  6. Listens on a random port for commands from the hacker.


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: Robert X Wang

Discovered: April 29, 2003
Updated: February 13, 2007 12:00:40 PM
Also Known As: Backdoor.Assasin.20 [KAV]
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP


These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Reverse the changes that the Trojan made to the registry and restart the computer.
  2. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as Backdoor.Assasin.F.
  4. Delete the %System%\IDE folder.
For details on each of these steps, read the following instructions.

1. Reversing the changes that the Trojan made to the registry and restarting the computer

CAUTION
: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value: 

    IDE      %System%\IDE\ide.exe

  5. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
    RunServices

  6. In the right pane, delete the value:

    IDE      %System%\IDE\ide.exe

  7. Exit the Registry Editor.
  8. Restart the computer.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

3. Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.Assasin.F, click Delete.

4. Deleting the %System%\IDE folder
  1. Open Windows Explorer.
  2. Navigate to the %System% folder.

    NOTE: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. Locate the folder named IDE, right-click it, and choose Delete.
  4. Close Windows Explorer.


Writeup By: Robert X Wang