W32.DSS.Trojan

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Discovered: April 24, 2002
Updated: February 13, 2007 11:58:15 AM
Also Known As: Trojan.Win32.DSS
Type: Trojan Horse


W32.DSS.Trojan is a Trojan horse that inserts a small Web page onto the computer. This Web page is then launched in a hidden Internet Explorer window.

Antivirus Protection Dates

  • Initial Rapid Release version April 24, 2002
  • Latest Rapid Release version November 04, 2019 revision 019
  • Initial Daily Certified version April 24, 2002
  • Latest Daily Certified version November 04, 2019 revision 065
  • Initial Weekly Certified release date April 24, 2002

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


Technical Description


The inserted Web page contains code that waits for a given period of time. When the time period has expired, the inserted Web page activates another Web page, which contains a link to an advertising page for an adult Web site. This Web page downloads a new phone dialer onto your computer.

This Trojan is most likely to arrive in an email message, which includes an attachment named Openme.exe.

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.


Removal


Download the latest virus definitions, scan and delete any infected files, and remove the entries left by the Trojan. For Windows NT/2000/XP, this means editing the registry to remove the entries that are left by W32.DSS.Trojan. For Windows 95/98/Me, remove the Trojan entry from the Shell= line in the System.ini file.

To delete files that are detected as W32.DSS.TrojanWorm:

  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. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
  3. Run a full system scan.
  4. Delete all files that are detected as W32.DSS.Trojan.

To edit the registry:

NOTE: This step is for Windows NT/2000/XP only

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:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon
  4. In the right pane, edit the following value and remove openme.exe.

    Shell Explorer.exe  openme.exe

    To edit the entry, select the key, click Edit, and click Modify. Select Openme.exe in the Value Data field and press Delete. Click Yes to the prompts that appear.

    NOTE:
    When you have finished, the value should look like this:

    Shell Explorer.exe  
  5. Exit the Registry Editor.

To edit System.ini:

NOTES:
  • These steps are for Windows 95/98/Me only.
  • (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about 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 that you are about to edit when you save your changes to that file.
  1. Click Start, and click Run.
  2. Type the following, and then click OK.

    edit c:\windows\system.ini

    The MS-DOS Editor opens.

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

    shell = explorer.exe openme.exe
  4. If it exists, select openme.exe and then press Delete. When you have finished, only shell = explorer.exe should remain.
  5. Click File, and click Save.
  6. Click File, and click Exit.


Writeup By: Atli Gudmundsson