Win32/Hioles is a trojan that communicates with a command and control (C&C) server to retrieve and execute commands such as to install a reverse proxy and other actions.

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/Hioles is a trojan that communicates with a command and control (C&C) server to retrieve and execute commands such as to install a reverse proxy and other actions.


Win32/Hioles is present as a file with either an .EXE file extension, or as a dynamic library with a .DLL file extension.

When installed as an .EXE file, the trojan may be present as one of the following files:

  • %TEMP%\kb<six numbers>.exe (for example, "kb291709.exe")
  • %AppData%\kb<six numbers>.exe (for example, "kb291709.exe")
  • %TEMP%\svchost.exe
  • %AppData%\svchost.exe

The registry is modified to run the trojan at each Windows start.

In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Sets value: "<malware file name>"
To data: "<malware file name>"

When installed as a .DLL component, the trojan may be present as a randomly named file in one of the following file folders:

  • %windir%\System32\
  • %AppData%

An example file name is "UjharyAjsigc.dll" or similar. The registry is modified to run the DLL component at each Windows start. Below are example registry modifications made by the installation of the trojan:

In subkey: HKLM\System\CurrentControlSet\Control\SecurityProviders
Sets value: "SecurityProviders"
With data: "<other file names>, <trojan proxy DLL file name>"   

For example:


In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Sets value: "Windows Time"
With data: "rundll32.exe <trojan proxy DLL file name>, Entrypoint"

Win32/Hioles may inject its payload code into other processes, for example:

  • Task Manager (taskmgr.exe)
  • Windows Explorer (explorer.exe)
  • lsass.exe

Communicates with a remote server
The trojan attempts to register itself with a remote C&C server to establish communication and to receive instructional commands. Some observed server domains include the following:


Win32/Hioles could be instructed to perform the following actions:

  • update the C&C server address
  • function as a reverse proxy to the C&C server by using one the following protocols
    • Socks4
    • Socks5
    • HTTP
    • HTTPS

The proxy service could be used for virtually any purpose such as the following:

  • register an account with an email provider such as ""
  • browse websites
  • send spam email messages

Analysis by Shawn Wang


There are no common symptoms associated with this threat. Alert notifications from installed antivirus software may be the only symptoms.



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: Jan 18, 2012
This entry was updated on: Mar 13, 2012

This threat is also detected as:
No known aliases