Discovered: April 16, 2002
Updated: February 13, 2007 11:38:57 AM
Also Known As: TROJ_SUA.A, Downloader - W
Type: Trojan Horse
Systems Affected: Windows

Backdoor.Autoupder is a backdoor program that can be used as a distribution mechanism by worms or other malicious programs.

NOTE: Virus definitions dated prior to April 23, 2002 may detect this as Backdoor.Trojan or Downloader.Trojan.

Antivirus Protection Dates

  • Initial Rapid Release version April 23, 2002
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version April 23, 2002
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date April 23, 2002

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

Technical Description

Backdoor.Autoupder initially presents itself as a Windows Cabinet (.cab) file named This file contains the ActiveX control file CoolStuff.ocx and the setup information file CoolStuff.inf. This file is usually obtained by visiting a malicious Web site that then attempts to download and install to your computer. Currently, this is the only way that this Trojan is known to infect computers.

Once these files are installed, the ActiveX control checks the process list to see if any of the following programs are running:

  • Blackice.exe (Black Ice Defender)
  • Blackd.exe (Black Ice Defender)
  • Zonealarm.exe (ZoneAlarm Firewall)
  • Smc.exe (Sygate Personal Firewall)
  • Persfw.exe (Tiny Personal Firewall)
  • Lookout.exe (ISS Network Sniffer application)
  • Espwatch.exe (Esafe Protect Watch)
  • Mpftray.exe (McAfee Personal Firewall)
  • Serv95.exe (Esafe Eliashim)
  • Nisum.exe (Norton Internet Security)
  • Nmain.exe (Norton Internet Security)

If any of these processes are running, Backdoor.Autoupder will terminate itself and do nothing. Otherwise, Backdoor.Autoupder will attempt to connect to one of the following Web sites, depending on its version:
  • http:/ /
  • http:/ /

From one of the listed Web sites, Backdoor.Autoupder will try to download one or more of the following files and place them in the \Windows folder:
  • Ausvc.exe: This module may also download malicious packages from one of the two listed Websites, and may install these packages on the victim's computer.
  • Bvt.exe: This module is referred to as the Browser Event component. It appears to have listening functions which allow backdoor capabilities.
  • Mnsvc.exe: This module connects to one of the two listed Websites, and checks if there are any new updated versions of the backdoor Trojan.
  • Absr.exe: This module is referred to as the Auto Browser component. It appears to be trying to connect to any random Website.

It is possible that Backdoor.Autoupder will download other files instead. If one of the files has been downloaded successfully, Backdoor.Autoupder will terminate these processes if they are running, and execute the newly downloaded versions.

Upon execution of the downloaded executables, and depending on which file was executed, Backdoor.Autoupder adds one of the following values:
  • SysScan C:\WINDOWS\bvt.exe
  • ausvc C:\WINDOWS\ausvc.exe
  • ABsr C:\WINDOWS\absr.exe
  • mnsvc C:\WINDOWS\mnsvc.exe

to the registry key


Backdoor.Autoupder may add one or more of the following subkeys:


to the registry key:


It may add the following (or other) subkeys:


to the registry key


It may add the following (or other) subkeys:


to the following registry key:


Backdoor.Autoupder is also capable of checking for the presence of newer versions of itself on specific Web sites and silently updating itself. Backdoor.Autoupder has strings embedded inside its program that may refer to commands used to remotely control the victim's computer.


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.


There are two ways to remove Backdoor.Autoupder

Use the Removal Tool
This is the easiest way to do this and is the recommend method. Symantec Security Response has provided a tool to remove infections of Backdoor.Autoupder. The tool is available here .

Manual removal
This should be used only if the tool does not work or if you cannot obtain it.

Here is an overview of the steps that are required to remove Backdoor.Autoupder (detailed instructions follow):

  • Disable System Restore (Windows Me/XP only)
  • Configure Windows to show all files
  • Delete temporary files and empty the Recycle Bin
  • Restart the computer in Safe mode
  • Delete files that are detected as Backdoor.Autoupder
  • Remove the values and keys that the Backdoor.Autoupder added to the registry

NOTE: Virus definitions dated prior to April 23, 2002, may detect this as Backdoor.Trojan or Downloader.Trojan.

To disable System Restore (Windows Me/XP only):
Windows Me and Windows XP users should temporarily turn off System Restore. This feature, which is enabled by default, is used by Windows Me/XP to restore files on your computer in case they become damaged. When a computer is infected with a virus, worm, or Trojan, it is possible that the virus, worm, or Trojan could be backed up by System Restore. By default, Windows prevents System Restore from being modified by outside programs. As a result, there is the possibility that you could accidentally restore an infected file, or that on-line scanners would detect the threat in that location. For instructions on how to turn off System Restore, read your Windows documentation or one of the following articles:
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article Anti-Virus Tools Cannot Clean Infected Files in the _Restore Folder , Article ID: Q263455.

NOTE: Do not reenable System Restore until the removal is finished and you have restarted the computer in normal mode

To configure Windows to show all files:

  1. Start Windows Explorer.
  2. Click the View menu (Windows 95/98/NT) or the Tools menu (Windows Me/2000/XP), and then click Options or "Folder options."
  3. Click the View tab.
  4. Uncheck "Hide file extensions for known file types."
  5. Do one of the following:
    • Windows 95/NT: Click "Show all files."
    • Windows 98: In the Advanced settings box, under the "Hidden files" folder, click Show all files.
    • Windows Me/2000/XP: Uncheck "Hide protected operating system files," and under the "Hidden files" folder, click "Show hidden files and folders."
  6. Click Yes if you see a Warning dialog box.
  7. Click Apply, and then click OK.

To delete temporary files and empty the Recycle Bin:
  1. Double-click the My Computer icon on the Windows desktop.
  2. Click once anywhere in the Address bar to select all the text.

  3. Type %temp% and then press Enter:

  4. The \Temp folder for the currently logged-on user appears.
  5. Click Edit, and then click Select All. Press Delete, and click Yes if you are asked to confirm the deletion.
  6. Close the My Computer window.
  7. On the Windows desktop, right-click the Recycle Bin, and then click Empty Recycle Bin.

To delete files that are detected as Backdoor.Autoupder:
  1. Obtain the most recent virus definitions. There are two ways to do this:
    • Run LiveUpdate. LiveUpdate is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
    • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

      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. Restart the computer in Safe mode. All Windows 32-bit operating systems except Windows NT can be restarted in Safe mode. Read the document for your version of Windows.
  3. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files.
  4. Run a full system scan.
  5. Delete all files that are detected as Backdoor.Autoupder, Backdoor.Trojan, or Downloader.Trojan.
  6. Use Windows Explorer to navigate into the Downloaded Program Files folder which is located in your Windows directory. If an ActiveX control named IO Class is found, delete this file.

To remove the values and keys that Backdoor.Autoupder added to the registry:

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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions
  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 key:

  4. In the right pane, delete any of the following values that exist:

    SysScan C:\WINDOWS\bvt.exe
    ausvc C:\WINDOWS\ausvc.exe
    ABsr C:\WINDOWS\absr.exe
    mnsvc C:\WINDOWS\mnsvc.exe
  5. Navigate to the following key:

  6. Delete any of the following subkeys that exist:


  7. Navigate to the following key:

  8. Delete the following registry subkey if it exists:

  9. Navigate to the following key:

  10. Delete the following registry subkey if it exists:

  11. Click Registry, and click Exit.

Restart the computer and run a full system scan. Reenable System Restore if running Windows Me/XP.

Writeup By: Cary Ng