Discovered: February 19, 2003
Updated: February 13, 2007 11:43:16 AM
Type: Trojan Horse
Systems Affected: Windows
The Backdoor.Assasin.E Trojan is a variant of Backdoor.Assasin . The Trojan gives a hacker unauthorized access to the compromised computer. It attempts to terminate the active processes of various firewalls, as well as antivirus and security products. This variant also attempts to spread itself across the network shares.
Backdoor.Assasin.E is written in the Borland Delphi programming language and is compressed with UPX.
Antivirus Protection Dates
- Initial Rapid Release version February 20, 2003
- Latest Rapid Release version November 04, 2019 revision 019
- Initial Daily Certified version February 20, 2003
- Latest Daily Certified version November 04, 2019 revision 065
- Initial Weekly Certified release date February 20, 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
When Backdoor.Assasin.E runs, it does the following:
- Creates a folder, C:\%Windir%\Win Types, and then copies itself to this folder as:
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.
- Creates the following components:
C:\%Windir%\Win Types\Win Const00.dll
C:\%Windir%\Win Types\Win Const01.dll
C:\%Windir%\Win Types\Win Const02.dll
NOTE: The .dll files are not viral by themselves, and thus, Symantec antivirus products do not detect them.
- Adds a value:
Hrxmp C:\%Windir%\win types\Win Const.exe
to the registry key:
so that the worm runs when you restart Windows.
- Attempts to terminate the active processes of several security products.
- Sends the ICQ pager and/or email to notify the hacker as soon as the compromised system is connected to the Internet.
- Opens randomly changed TCP and UDP ports to connect to the hacker. Once the connection is established, the Trojan listens for the following remote commands to perform:
- Steal the system and network information
- Query/Change the Registered Organization and Registered Owner settings in the registry keys
- Query/Change the Internet Explorer security settings
- Modify the Internet Explorer home Page
- Log keystrokes
- Open/Close CD-ROM drive
- Screen capture
- Perform a Denial of Service (DoS) attack on any Web Site, depending on the hacker's choice.
- Inventories the network-shared disks. Backdoor.Assasin.E copies itself to each shared disks it finds.
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.
These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
- Update the virus definitions.
- Do one of the following:
- Windows 95/98/Me: Restart the computer in Safe mode.
- Windows NT/2000/XP: End the Trojan process.
- Run a full system scan and delete all the files detected as Backdoor.Assasin.E.
Remove the folder, C:\%Windir%\Win Types.
- Reverse the changes that the Trojan made to the registry.
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. Restarting the computer in Safe mode or ending the Trojan process
- Windows 95/98/Me
Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document, "How to start the computer in Safe Mode."
To end the Trojan process:
- Press Ctrl+Alt+Delete once.
- Click Task Manager.
- Click the Processes tab.
- Double-click the Image Name column header to alphabetically sort the processes.
- Scroll through the list and look for Backdoor.Assasin.E.
- If you find the file, click it, and then click End Process.
- Exit the Task Manager.
- Start your Symantec antivirus program and make sure that it is configured to scan all the files.
- For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
- For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan All Files."
- Run a full system scan.
- If any files are detected as infected with Backdoor.Assasin.E, click Delete.
4. Reversing the changes made 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 the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
- Click Start, and then click Run. (The Run dialog box appears.)
- Type regedit
Then click OK. (The Registry Editor opens.)
- Navigate to the key:
- In the right pane, delete the value:
Hrxmp C:\%Windir%\win types\Win Const.exe
- Exit the Registry Editor.
Writeup By: Yana Liu