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Win32/Cleaman


Win32/Cleaman is a family of multi-component, obfuscated trojans that are distributed via drive-by exploit kits. Its main purpose is to redirect Bing, Google, and Yahoo search results to bogus webpages that serve advertisements, adware programs, and malware.



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 http://www.microsoft.com/windows/antivirus-partners/.

Additional remediation instructions for Win32/Cleaman:

This threat may make lasting changes to a computer's configuration that are NOT restored by detecting and removing this threat. For more information on returning an infected computer to its pre-infected state, please see the following article/s:

Recreating a clean Hosts file: http://support.microsoft.com/kb/972034

Threat behavior

Win32/Cleaman is a family of multi-component, obfuscated trojans that are distributed via drive-by exploit kits. Its main purpose is to redirect Bing, Google, and Yahoo search results to bogus webpages that serve advertisements, adware programs, and malware.

Installation

Win32/Cleaman is usually distributed by drive-by exploits kit. We have seen members of this family bundled with exploits that are variants of Exploit:Java/CVE-2010-0840 and Exploit:Java/CVE-2011-3544. It usually arrives protected by custom packers, injectors, or crypters, for example, VirTool:Win32/CeeInject.gen!DZ.

Win32/Cleaman creates .EXE and .DLL components with any of the following names:

  • %AppData%\dplaysvr.exe
  • %AppData%\bhelper.exe
  • %AppData%\cleanddm.exe
  • %AppData%\cleanhdd.exe
  • %AppData%\cleanhdm.exe
  • %AppData%\cleanhelper.exe
  • %AppData%\cleanhlm.exe
  • %AppData%\cleanhtm.exe
  • %AppData%\cleanmgr.exe
  • %AppData%\compmgm.exe
  • %AppData%\volmgr.exe
  • %AppData%\dplayx.dll
  • %AppData%\bhelper.dll
  • %AppData%\cleanddm.dll
  • %AppData%\cleanhdd.dll
  • %AppData%\cleanhdm.dll
  • %AppData%\cleanhelper.dll
  • %AppData%\cleanhlm.dll
  • %AppData%\cleanhtm.dll
  • %AppData%\cleanmgr.dll
  • %AppData%\compmgm.dll
  • %AppData%\volmgr.dll

Note: Some of the file names of the drop files listed here are similar to clean Windows system files.

Win32/Cleaman also creates the following registry entries to ensure that its dropped files run every time Windows starts.

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "<malware value>"
With data: "%AppData%\<malware file>.exe"

In subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "<malware value>"
With data: "%AppData%\<malware file>.exe"

For example:

In subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "dplaysvr"
With data: "%AppData%\dplaysvr.exe"

Win32/Cleaman may create a .LNK file in <common startup folder>, which points to the malware file. The .LNK file name is the same as the .EXE component.

It may also create a randomly-named empty text file as an infection marker.

It then connects to an attacker's website to send the following information:

  • Identifier and version of itself
  • Infected computer's name

Win32/Cleaman hooks the following APIs to redirect Internet access and also to hide its malicious files, threads and process, and registry entries:

  • Within ntdll.dll
    • ntresumethread
    • ntenumeratevaluekey
    • ntquerysysteminformation
    • ldrloaddll
  • Within kernel32.dll
    • findfirstfilea
    • findnextfilea
    • findfirstfilew
    • findnextfilew
  • Within ws2_32.dll
    • connect
Payload

Modifies Hosts file

Win32/Cleaman modifies the Windows Hosts file by adding the following values:

  • 80.79.117.219 www.google.com
  • 80.79.117.220 search.yahoo.com
  • 80.79.117.220 www.bing.com

Redirects web searches

Win32/Cleaman monitors the user's web browsing behavior, and redirects the browser if you visit certain websites. When you visit Bing, Google, or Yahoo to do web searches, your browser is redirected to a specific IP address, for example, "80.79.117.219".

Analysis by Rodel Finones


Symptoms

System changes

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

  • The presence of any of the following files:
    • %AppData%\dplaysvr.exe
    • %AppData%\bhelper.exe
    • %AppData%\cleanddm.exe
    • %AppData%\cleanhdd.exe
    • %AppData%\cleanhdm.exe
    • %AppData%\cleanhelper.exe
    • %AppData%\cleanhlm.exe
    • %AppData%\cleanhtm.exe
    • %AppData%\cleanmgr.exe
    • %AppData%\compmgm.exe
    • %AppData%\volmgr.exe
    • %AppData%\dplayx.dll
    • %AppData%\bhelper.dll
    • %AppData%\cleanddm.dll
    • %AppData%\cleanhdd.dll
    • %AppData%\cleanhdm.dll
    • %AppData%\cleanhelper.dll
    • %AppData%\cleanhlm.dll
    • %AppData%\cleanhtm.dll
    • %AppData%\cleanmgr.dll
    • %AppData%\compmgm.dll
    • %AppData%\volmgr.dll
  • Your Hosts file may have entries similar to the following:
    • 80.79.117.219 www.google.com
    • 80.79.117.220 search.yahoo.com
    • 80.79.117.220 www.bing.com

Prevention

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 http://www.microsoft.com/windows/antivirus-partners/.

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.

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 http://www.microsoft.com/security/online-privacy/passwords-create.aspx.


Alert level: Severe
This entry was first published on: May 28, 2012
This entry was updated on: Jun 11, 2012

This threat is also detected as:
No known aliases