Win32/Bocinex is a detection for a family of malware that launches a Bitcoin mining client, detected as Program:Win32/CoinMiner. The client is configured to attribute newly generated Bitcoin digital cash, or "BTC", to an attacker's Bitcoin account.

What to do now

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

For more information on antivirus software, see

Threat behavior

Win32/Bocinex is a detection for a family of malware that launches a Bitcoin mining client, detected as Program:Win32/CoinMiner. The client is configured to attribute newly generated Bitcoin digital cash, or "BTC", to an attacker's Bitcoin account.


Win32/Bocinex may be encountered as an attachment to spam email, when visiting links sent via instant messaging, or by downloading its installer that is disguised as another wanted application. The installer is often a randomly named file that is in the form of a self-extracting executable archive (RarSFX), as in "169E.exe" or "9D1A.exe" for example. The name of the Win32/Bocinex trojan file and path of installation is specified in the RarSFX installer script, as in the following example:

Path=%USERPROFILE%\Start Menu\Programs\Startup

In the above example, the script instructs the installer to write the trojan as the following:

%USERPROFILE%\Start Menu\Programs\Startup\x10.exe (e.g. "C:\Users\Administrator\Start Menu\Programs\Startup\x10.exe")

The installed file is another RarSFX dropper and runs when Windows starts. The archive file contains another installation script that specifies where the archive file contents are dropped, and which file to execute, for example:


The above script instructs the dropper to execute the file "%TEMP%\Winlogons.exe", which is a copy of Win32/Bocinex. The archive contains a Bitcoin mining client, which may be present as "%TEMP%\xC.exe".


Executes Program:Win32/CoinMiner

Win32/Bocinex executes the BTC mining client in a manner that attributes newly generated Bitcoins to an account specified by an attacker, for example:

%TEMP%\xC.exe -a 60 -g yes -o <URL> -u <attacker user name> -p <attacker password>

When the mining client "xC.exe" executes, there may be a noticeable increase in CPU utilization that is observed as a sluggish response or slow execution of other applications.

Analysis by Alden Pornasdoro


System changes

The following system changes may indicate the presence of this malware:

  • The presence of the following file in the Temporary files folder:
  • Your computer may experience above average CPU usage


Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to webpages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites. Instructions on how to download the latest versions of some common software is available from the following:

You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see

Limit user privileges on the computer

Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.

You can configure UAC in your computer to meet your preferences:

Use caution when opening attachments and accepting file transfers

Exercise caution with email and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.

Use caution when clicking on links to webpages

Exercise caution with links to webpages that you receive from unknown sources, especially if the links are to a webpage that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a webpage with harmful content.

Avoid downloading pirated software

Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.

Protect yourself from social engineering attacks

While attackers may attempt to exploit vulnerabilities in hardware or software to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.

Use strong passwords

Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least eight characters, and combines letters, numbers, and symbols. For more information, see

Alert level: Severe
This entry was first published on: Mar 08, 2012
This entry was updated on: Apr 06, 2012

This threat is also detected as:
No known aliases