Backdoor.Anyserv.B

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Discovered: April 14, 2004
Updated: February 13, 2007 12:21:22 PM
Type: Trojan Horse
Systems Affected: Windows


Backdoor.Anyserv.B is a Trojan horse that gives an attacker remote access to an infected computer.

This threat is written in C++ and is packed with ASPack.

Virus definitions dated April 14, 2004 or earlier may detect this threat as Backdoor.Wasax.

Antivirus Protection Dates

  • Initial Rapid Release version April 14, 2004
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version April 14, 2004
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date April 14, 2004

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

Writeup By: John Canavan

Discovered: April 14, 2004
Updated: February 13, 2007 12:21:22 PM
Type: Trojan Horse
Systems Affected: Windows




Note: The samples of Backdoor.Anyserv.B that Symantec Security Response has received have not been complete. Backdoor.Anyserv.B may perform actions that are not described here.


When Backdoor.Anyserv.B is executed, it performs the following actions:
  1. Injects the Rasaccs.dll file into Svchost.exe, so that it can run unnoticed.

  2. May copy several .dll and executable files to the %Windir% folder.


    Note: %Windir% is a variable. The Trojan locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies the files to that location.

  3. May attempt to hijack the "Routing and Remote Access" service by setting the value:

    "ServiceDLL" = "%Windir%\rasaccs.dll"

    in the registry key:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RemoteAccess\Parameters

  4. Monitors keystrokes and logs them to a file in the %Temp% folder.


    Note: %Temp% is a variable. The Trojan locates the temporary folder and creates the log file in that location. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).

  5. Registers a temporary Internet address with tzo.com and notifies the attacker of the infection.

  6. Listens on port 1129 for connections.

  7. When a connection is accepted, the attacker can perform any of the following actions on an infected computer:
    • Restart or shut down
    • View a list of running processes
    • Stop processes
    • Open an FTP connection
    • View a log of system information
    • Collect keystroke log files
    • Download and execute a file from a specified Internet address
    • Perform brute-force dictionary attacks on a specified remote host


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: John Canavan

Discovered: April 14, 2004
Updated: February 13, 2007 12:21:22 PM
Type: Trojan Horse
Systems Affected: Windows


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

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Restart the computer in Safe mode or VGA mode.
  4. Run a full system scan and delete all the files detected as Backdoor.Anyserv.B.
  5. Delete the value that was added to the registry.
For details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation or one of the following articles:
Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

For additional information and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. To update 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; read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document "How to start the computer in Safe mode."
  • For Windows NT 4 users, restart the computer in VGA mode.
4. To scan for and delete 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.Anyserv.B, click Delete.

5. To delete the value that was added to the registry


WARNING: 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\System\CurrentControlSet\Services\RemoteAccess\Parameters

    (The \Parameters subkey may not exist on all the systems. If it does not, go to step f.)

  4. If the In the right pane, double-click:

    ServiceDLL

  5. Change the text in the Value data box to:

    %SystemRoot%\System32\mprdim.dll

    and then click OK.

  6. Exit the Registry Editor.

  7. Restart the computer in normal mode.


Writeup By: John Canavan