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SystemTool


System Tool is a variant of Win32/Winwebsec - a family of programs that claims to scan for malware and displays fake warnings of "malicious programs and viruses". They then inform the user that he or she needs to pay money to register the software to remove these non-existent threats.

Win32/Winwebsec has been distributed with many different names. The name used by the malware, the user interface and other details vary to reflect each variant's individual branding. The following details describe Win32/Winwebsec when it is distributed with the name "System Tool".



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/.

Threat behavior

System Tool is a variant of Win32/Winwebsec - a family of programs that claims to scan for malware and displays fake warnings of "malicious programs and viruses". They then inform the user that he or she needs to pay money to register the software to remove these non-existent threats.

Win32/Winwebsec has been distributed with many different names. The name used by the malware, the user interface and other details vary to reflect each variant's individual branding. The following details describe Win32/Winwebsec when it is distributed with the name "System Tool".

Installation

When distributed as "System Tool", Win32/Winwebsec creates a folder under %AppData% (for a specific user or for all users) with a randomly-generated name (for example, "%AppData%\nGfKl00902"). The fake scanner is copied to this folder, using the same name as that of the folder (for example "%AppData%\nGfKl00902\nGfKl00902.exe").

It modifies the registry to ensure that the rogue is executed at each Windows start:

In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce
Sets value: "<malware file name without the extension>" (for example, "nGfKl00902")
With data: "<malware path and file name>" (for example, "%AppData%\nGfKl00902\nGfKl00902.exe")

It also creates the following shortcuts to the rogue on the desktop and in the Start>Programs folder:

  • %HOMEPATH%\Desktop\System Tool 2011.lnk
  • %UserProfile%\Start Menu\Programs\System Tool\System Tool 2011.lnk
Payload

Displays false/misleading malware alerts

When run, System Tool performs a fake scan of the system, and falsely claims that a number of files on the system are infected with malware. Should users request that it clean the reported infections, it advises them that they need to pay money to register the program in order for it to do so.

Some examples of the interface, fake alerts, fake scanning results, and popups displayed by "System Tool" are shown below:

Terminates processes

After installation, and upon each subsequent re-boot of the system, System Tool prevents the user from launching any application by terminating its process and displaying a message that falsely claims that the process is infected. For instance, if "notepad.exe" is launched, the malware displays the following dialog:

Win32/Winwebsec, however, avoids terminating the following processes:

  • aeadisrv.exe
  • alg.exe
  • audiodg.exe
  • csrss.exe
  • conhost.exe
  • ctfmon.exe
  • dwm.exe
  • explorer.exe
  • httpd.exe
  • iastordatamgrsvc.exe
  • iexplore.exe
  • lsass.exe
  • lsm.exe
  • mfnsvc.exe
  • mdnsresponder.exe
  • nvscpapisvr.exe
  • nvvsvc.exe
  • nvsvc.exe
  • pdagent.exe
  • searchindexer.exe
  • services.exe
  • slsvc.exe
  • smss.exe
  • snort.exe
  • spoolsv.exe
  • svchost.exe
  • taskhost.exe
  • wininit.exe
  • winlogon.exe
  • wmiprvse.exe
  • winroute.exe
  • wscntfy.exe

It also changes Desktop wallpaper to the following image (located at %temp%\<random file name>.tmp):

It may also display a fake error image (located at %temp%\<random file name>.bmp)

Analysis by Elda Dimakiling


Symptoms

System changes
The following system changes may indicate the presence of this malware:
  • You see the following fake security program:
  • The presence of the following files:
    %AppData%\nGfKl00902\nGfKl00902.exe
  • The presence of the following registry modifications:
  • In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce
    Data: "nGfKl00902"
    Value: "%AppData%\nGfKl00902\nGfKl00902.exe"
  • You get a similar popup when certain processes try to run:
  • Your desktop wallpaper changes to the following:
  • You see the following fake warnings:
 

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.
 
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. 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 http://www.microsoft.com/protect/yourself/password/create.mspx.

Alert level: Low
This entry was first published on: Mar 15, 2011
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Win32/Winwebsec (other)
  • Rogue:Win32/Winwebsec (other)
  • System Tool (other)
  • MS Removal Tool (other)