Class
Trojan-Downloader
Platform
Win32

Parent class: TrojWare

Trojans are malicious programs that perform actions which are not authorized by the user: they delete, block, modify or copy data, and they disrupt the performance of computers or computer networks. Unlike viruses and worms, the threats that fall into this category are unable to make copies of themselves or self-replicate. Trojans are classified according to the type of action they perform on an infected computer.

Class: Trojan-Downloader

Programs classified as Trojan-Downloader download and install new versions of malicious programs, including Trojans and AdWare, on victim computers. Once downloaded from the Internet, the programs are launched or included on a list of programs which will run automatically when the operating system boots up. Information about the names and locations of the programs which are downloaded are in the Trojan code, or are downloaded by the Trojan from an Internet resource (usually a web page). This type of malicious program is frequently used in the initial infection of visitors to websites which contain exploits.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.

Description

Technical Details

This Trojan downloads files via the Internet without the user’s knowledge or consent.

It is a Windows PE EXE file. It is written in Borland C++. It has the following components:

  • CLIENT.EXE — 57 344 bytes
  • SERVER.EXE — 65 024 bytes
  • X.EXE — 4 096 bytes

Payload

The Trojan program (X.EXE) attempts to establish a TCP connection to 116.116.199.216:62324 (216.216.216.216:55512). If a connection is not established within 30 seconds, the Trojan will terminate its process. If a connection is established, the Trojan will create a file called “anyfile.exe” in the current directory, write downloaded data to this file, and then launch the file for execution. The Trojan will then cease running.

The Trojan uses a ZFTP server on port 12345 to download data. When the client component (CLIENT.EXE) is launched, it sends a broadband request to check port 12345. If the address of the computer where the server component (SERVER.EXE) is installed is given as a command line parameter, then a connection will be established to this machine on the designated port. Files will then be downloaded from the server.

Removal instructions

  1. Use Task Manager to terminate the Trojan process.
  2. Delete the original Trojan files (the location will depend on how the program originally penetrated the victim machine).
  3. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).

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Find out the statistics of the vulnerabilities spreading in your region on statistics.securelist.com

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