Trojan-Downloader.Java.OpenConnection.dd

Technical Details

This Trojan downloads files from the Internet and launches them without the user's knowledge. It is a Java class file. It is 4588 bytes in size.

Payload

The malware is a component of a Trojan downloader from the "Trojan-Downloader.Java.OpenConnection" family and includes a class file named "bear", which downloads a file from the Internet, from a link sent to it, and launches the downloaded file for execution. The downloaded file is saved in the current user's temporary files directory as

%Temp%\<rnd>.exe

where is a random fractional decimal number between 0 and 1. Before downloading, it checks the name of the OS installed on the infected system. If the OS is not Windows, the download does not take place.

The Trojan constitutes a Java applet. It is launched from an infected HTML page using an "<APPLET>" tag, for which an encrypted link to a downloadable file is sent in parameter named "pid".

As well as the above-mentioned class file, the Trojan contains "Unicode" and "UTF" class files. The "Unicode" class file includes "lopiyo" function, which is used to decrypt the link to a downloadable file. The "UTF" class file contains a code designed to exploit a vulnerability (CVE-2010-0840).

Removal instructions

If your computer does not have antivirus protection and has been infected by this malicious program, follow the instructions below to delete it:

1. Update Sun Java JRE and JDK to the latest versions.
2. Delete the following file:

   %Temp%\<rnd>.exe

3. Empty the Temporary Internet Files directory, which may contain infected files (see How to delete infected files from Temporary Internet Files folder?).

   %Temporary Internet Files%