Backdoor.Amitis

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Discovered: January 07, 2003
Updated: February 13, 2007 11:56:50 AM
Also Known As: Backdoor.Amitis.12
Type: Trojan Horse
Systems Affected: Windows


The Backdoor.Amitis Backdoor Trojan gives an attacker unauthorized access to an infected computer. By default, the Trojan opens TCP port 27,551 on the infected computer. This threat is written in Microsoft Visual Basic, version 6.

Antivirus Protection Dates

  • Initial Rapid Release version January 07, 2003
  • Latest Rapid Release version January 15, 2018 revision 020
  • Initial Daily Certified version January 07, 2003 revision 002
  • Latest Daily Certified version January 15, 2018 revision 024
  • Initial Weekly Certified release date January 08, 2003

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

Writeup By: Kaoru Hayashi

Discovered: January 07, 2003
Updated: February 13, 2007 11:56:50 AM
Also Known As: Backdoor.Amitis.12
Type: Trojan Horse
Systems Affected: Windows


When Backdoor.Amitis runs, it does the following:

  1. Copies itself to the %Windir% folder. The file name is not fixed, and the name of the copied file name is the same as the one you executed. For example, if the Trojan file name is Server.scr, it copies itself as %Windir%\Server.scr, when you run Server.scr.

    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. If the operating system is Windows 95/98/Me, the Trojan may add a reference to itself to the Run= and load= lines in the [windows] section of the Win.ini file. For example:

    [windows]
    run=%windir%\<file name of Trojan>
    load==%windir%\<file name of Trojan>

    so that the Trojan starts each time you start Windows.
  3. On Windows NT/2000/XP, the Trojan adds the value:

    load %windir%\<file name of Trojan>open=%windir%\<filename>

    to the registry keys:

    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    HKEY_USER\<User ID>\Software\Microsoft\Windows NT\CurrentVersion\Windows

    Because this command is not correctly formatted, the Trojan does not start when you start Windows on these operating systems.
  4. Opens TCP port 27,551 to wait for a connection 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: Kaoru Hayashi

Discovered: January 07, 2003
Updated: February 13, 2007 11:56:50 AM
Also Known As: Backdoor.Amitis.12
Type: Trojan Horse
Systems Affected: Windows


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

  1. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as Backdoor.Amitis.
  3. Edit the files. Do one of the following:
    • Windows 95/98/Me: Edit the Win.ini file and remove the text that the Backdoor Trojan added to the run= and load= lines.
    • Windows NT/2000/XP: Edit the registry and remove the lines that the Backdoor Trojan added to the \Run key.
For details on each of these procedures, read the following instructions.

1. 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 the 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), in the "Protection" section, at the top of this writeup.
  • 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), in the "Protection" section, at the top of this writeup.
    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.
2. Scanning for and deleting the infected files detected as Backdoor.Amitis
  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.Amitis, click Delete.

3. Editing the files

Do one of the following:
    • Windows 95/98/Me: Edit the Win.ini file and remove the text that the Backdoor Trojan added to the run= and load= lines.
    • Windows NT/2000/XP: Edit the registry and remove the lines that the Backdoor Trojan added to the \Run key.
For detailed information on editing files, read the following instructions.

Editing the Win.ini file
This is necessary only if you are running Windows 95/98/Me.

NOTE for Windows Me users only: Due to the file-protection process in Windows Me, a backup copy of the file you are to edit exists in the C:\Windows\Recent folder. Symantec recommends that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:\Windows\Recent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file you are to edit, when you save your changes to that particular file.
  1. Click Start, and then click Run.
  2. Type the following, and then click OK.

    edit c:\windows\win.ini

    (The MS-DOS Editor opens.)

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.
  3. In the [windows] section of the file, look for an entry similar to:

    load=%windir%\<file name of Trojan>
  4. Select the entire line. Be sure that you have not selected any other text, and then press Delete.
  5. In the [windows] section of the file, look for a line similar to:

    run=%windir%\<file name of Trojan>
  6. If it exists, select the entire line. Be sure that you do not select any other text, and then press Delete.
  7. Click File, and then click Save.
  8. Click File, and then click Exit.

    Editing the registry
    This is necessary only if you are running Windows NT/2000/XP.

    CAUTION : Symantec strongly recommends that you back up the registry before you make 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, and then click OK. (The Registry Editor opens.)
    3. Navigate to the key:

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

      load %windir%\<file name of Trojan>open=%windir%\<filename>
    5. Navigate to the key:

      HKEY_USER\<User ID>\Software\Microsoft\Windows NT\CurrentVersion\Windows
    6. In the right pane, delete the value:

      load %windir%\<file name of Trojan>open=%windir%\<filename>
    7. Exit the Registry Editor.


    Writeup By: Kaoru Hayashi