Home / malware Trojan:W32/Fixer
First posted on 18 August 2009.
Source: SecurityHomeAliases :
There are no other names known for Trojan:W32/Fixer.
Explanation :
A trojan, or trojan horse, is a seemingly legitimate program which secretly performs other, usually malicious, functions. It is usually user-initiated and does not replicate.
Additional DetailsTrojan:W32/Fixer is a malicious program that demands a ransom from the user by encrypting and disabling documents and media files. The only way to decrypt the files is by purchasing a program being offered by the malware author(s). As such, this malware is a type of Ransomware.
The details below apply to the Trojan:W32/Fixer.A variant.
Installation
The trojan's main component is a DLL that is dropped to:
  • %system%fpfstb.dll
This DLL is injected into almost all running processes. It is not injected into some executables, including:
  • smss.exe   • csrss.exe   • winlogon.exe
It adds a launchpoint in the registry as below:
  • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWindows
AppInit_DLLs = "%system%fpfstb.dll"
It creates these registries probably as infection markers:
  • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWOWkeyboard
is_installed = [random string]   • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWOWkeyboard
id = [random string]
Activity
Once installed, the DLL encrypts files with the following extensions to disable them :
  • ppsm   • ppsx   • ppam   • potm   • potx   • pptm   • pptx   • xlam   • xlsb   • xltm   • xltx   • xlsm   • xlsx   • dotm   • dotx   • docm   • docx   • pst   • mdb   • wma   • mp3   • png   • jpeg   • jpg   • pdf   • ppt   • xls   • doc
Any newly created files on the system that use one of the extensions listed above are also encrypted.
When user tries to open the encrypted files a screen like below is shown:
It also shows a popup like below at the bottom right corner on the system tray :
The only way for users to fix the so-called corrupted files is to purchase the FileFixPro program. If the "repair file" option is selected, user will be directed to this site:
  • http://www.filefixpro.com/[...]/download.php
The downloaded program is a scanner that will show a screen like below:Last update 18 August 2009
