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Malicious Software Encyclopedia: WinNT/FURootkit

Published: February 28, 2008

Virtool:WinNT/FURootkit is a family of kernel-mode rootkit programs that target computers running certain versions of Microsoft Windows. It is primarily used to hide certain processes from process viewers or to hide certain device drivers. This rootkit is often bundled with other malicious software. For example, it is installed on a computer by some variants of Win32/Rbot.
 
Some variants of WinNT/FURootkit can be configured to unlink certain processes from the EPROCESS linked list, so that the running process is hidden from Task Manager and other process-viewer applications. Some Win32/Rbot variants use this stealth method to hide themselves.

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On This Page
Threat OverviewThreat Overview
Technical AnalysisTechnical Analysis
How to Prevent InfectionHow to Prevent Infection
How to Tell If Your Computer Is InfectedHow to Tell If Your Computer Is Infected
How to Recover from InfectionHow to Recover from Infection

Threat Overview

Class/typeTrojan - Rootkit-Stealth
DiscoveredFebruary 25, 2005
CirculatingYes
Affected operating systemsWindows 2000
Windows XP
Windows Server 2003
Affected software Not specified
Infection ratingLow
Recovery difficultyDifficult
Damage ratingLow
Transmission ratingLow

Technical Analysis

Virtool:WinNT/FURootkit is a family of kernel-mode rootkit programs that target computers running certain versions of Microsoft Windows. It is primarily used to hide certain processes from process viewers or to hide certain device drivers. This rootkit is often bundled with other malicious software. For example, it is installed on a computer by some variants of Win32/Rbot.
 
Some variants of WinNT/FURootkit can be configured to unlink certain processes from the EPROCESS linked list, so that the running process is hidden from Task Manager and other process-viewer applications. Some Win32/Rbot variants use this stealth method to hide themselves.

How to Prevent Infection

Take the following steps to help prevent infection on your system:
  • Enable a firewall on your computer.
  • Get the latest computer updates.
  • Use up-to-date antivirus software.
  • Use caution with attachments and file transfers.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
  1. Click Start, and click Control Panel.
  2. Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
  3. Click Change Windows Firewall Settings.
  4. Select On.
  5. Click OK.
To turn on the Windows Firewall in Windows Vista
  1. Click Start, and click Control Panel.
  2. Click Security.
  3. Click Turn Windows Firewall on or off.
  4. Select On.
  5. Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows XP
  1. Click Start, and click Control Panel. 
  2. Click System.
  3. Click Automatic Updates.
  4. Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
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 that is updated with the latest signature files. Antivirus software is available from several sources. For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
Use caution with attachments and file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources.  Use extreme caution when accepting file transfers from known or unknown sources.

How to Tell If Your Computer Is Infected

How to Recover from Infection

Automatic Recovery
To attempt to automatically remove this threat, run one of the following removal tools:

Manual Recovery

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft online scanner (http://safety.live.com). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.

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