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Discovered: October 16, 2014
Updated: October 17, 2014 8:35:19 PM
Type: Trojan
Infection Length: Varies
Systems Affected: Windows

Trojan.Beginto is a Trojan horse that opens a back door and downloads files on the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version October 16, 2014 revision 016
  • Latest Rapid Release version September 22, 2016 revision 004
  • Initial Daily Certified version October 16, 2014 revision 018
  • Latest Daily Certified version September 22, 2016 revision 025
  • Initial Weekly Certified release date October 22, 2014

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

Technical Description

The Trojan may arrive on the compromised computer after being downloaded from the following location:

  • [http://][REMOVED]

The Trojan is composed of the following:
  • HTML file
  • JAR file
  • DLL file

Note: The DLL file is located inside the JAR file.

The HTML file is responsible for loading the JAR file.

The HTML file contains Base64 encoded shell code that is used by the JAR file.

When the JAR file is loaded, it decodes the Base64 encoded shell code.

The JAR file loads one of the following DLL files:
  • main.dll (for 32-bit Windows)
  • main64.dll (for 64-bit Windows)

The JAR file then calls the following:
  • Java_Main_inject

The DLL file creates a new notepad.exe process and injects malicious shell code into it.

The Trojan uses the shell code to open a back door and connect to the following location:
  • TCP port 7998

The Trojan downloads additional shell code which is also injected into the notepad.exe process.

The Trojan may then perform malicious actions on the compromised 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.