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Trojan-Dropper:W32/Hoaxer.B

First posted on 08 October 2008.
Source: SecurityHome

Aliases :

There are no other names known for Trojan-Dropper:W32/Hoaxer.B.

Explanation :

This type of trojan contains one or more malicious files, which it will secretly install on the system.

right]This malware drops and installs multiple files in the system. The cumulative effect of the malware is to produce a fake infection warning, which aims to frighten the user into purchasing a rogue antivirus program.

Installation
The malware installs a variety of files on the system.

These files are all detected as Trojan-Downloader.Win32.Hoaxer.a:

• %programfiles%PCHealthCenter.exe
• %programfiles%PCHealthCenter1.exe
• %programfiles%PCHealthCenter2.exe
• %programfiles%PCHealthCenter3.exe
• %programfiles%PCHealthCenter4.exe
• %programfiles%PCHealthCenter5.exe
• %programfiles%PCHealthCenter7.exe

These files are all image files used by the sc.html file:

• %programfiles%PCHealthCenter.gif
  
• %programfiles%PCHealthCenter1.gif
• %programfiles%PCHealthCenter2.gif
• %programfiles%PCHealthCenter3.gif
  

This file is the fake Windows Security Center warning:

• %programfiles%PCHealthCentersc.html

These icons are for links to pornography sites:

• %programfiles%PCHealthCenter1.ico
• %programfiles%PCHealthCenter2.ico

In addition to icons for links, the malware also adds actual links to the megafreeporn website:

• %desktop%QUALITY PORN.url
  
• %desktop%BEST ZOO PORN.url

These files are essentially duplicates of files which have been previously installed:

• c:x - same file as %programfiles%PCHealthCenter7.ex
• %windir%system32YUR.exe - same file as %programfiles%PCHealthCenter1.exe
• %windir%system32YUR.exe - same file as %programfiles%PCHealthCenter2.exe
• %windir%system32YUR.exe - same file as %programfiles%PCHealthCenter3.exe
• %windir%system32YUR.exe - same file as %programfiles%PCHealthCenter4.exe
• %windir%system321.ico - same as %programfiles%PCHealthCenter1.ico
• %windir%system322.ico - same as %programfiles%PCHealthCenter2.ico

Finally, the malware installs a file which is detected as Fraudtool:W32/SpywarePreventer.A:

• http://first-reason.com/data/x7/[...]/0000005378.exe

Registry

The malware also makes a number of registry changes in order to display the installed files. Sample registry values would be:

• HKLMSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR1.exe = C:Windowssystem32YUR1.exe
• HKCUSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR1.exe = C:Windowssystem32YUR1.exe
• HKLMSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR2.exe = C:Windowssystem32YUR2.exe
• HKCUSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR2.exe = C:Windowssystem32YUR2.exe
• HKLMSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR3.exe = C:Windowssystem32YUR3.exe
• HKCUSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR3.exe = C:Windowssystem32YUR3.exe
• HKLMSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR4.exe = C:Windowssystem32YUR4.exe
• HKCUSOFTWAREMicrosoftWindowsCurrentVersionRun
  YUR4.exe = C:Windowssystem32YUR4.exe

Execution
Upon execution, the malware will immediately display the sc.html file, which appears to be a Windows Security Center warning that the system is infected.



The user is asked if they would like to scan and remove the (supposed) threats detected, which is the recommended option. If the user clicks on the "Yes" option in the dialog box, the malware will open this link in the browser:

• http://scanner.vav-x-scanner.com/34/?advid=[...]5378&dsbndbinj&

The page opened contains the product that the malware is promoting.

Last update 08 October 2008

 

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