Trojan:Win32/FakeSysdef

Win32/FakeSysdef is a family of programs that claim to scan for hardware defects related to system memory, hard drives and over-all system performance. They scan the system, show fake hardware problems, and offer a solution to defrag the hard drives and optimize the system performance. They then inform the user that they need to pay money to download the fix module and to register the software in order to repair these non-existent hardware problems. One of the first variants was distributed as program named "HDD Defragmenter" hence the name "FakeSysdef" or "Fake System Defragmenter".

Win32/FakeSysdef has been distributed with several different names or aliases. The user interface and some other details vary to reflect each variant's individual branding.

The branding strategy may look legitimate to computer users as the names are usually a combination of technical words such as "HDD", "Disk", "Memory" and action words such as "Scanner", "Defragmenter", "Diagnostics", "Repair", and "Fix". Currently observed variants of FakeSysdef include the following:

• Check Disk
• Data Restore
• Data_Recovery
• Data Recovery
• Defragmenter
• Disk Defrag
• Disk Doctor
• Disk Helper
• Disk OK
• Disk Optimizer
• Disk Recovery
• Disk Repair
• Disk Tool
• Easy Scan
• Fast Disk
• File Recovery
• Full Scan
• Good Memory
• HDD Control
• HDD Defragmenter
• HDD Diagnostic
• HDD Fix
• HDD Low
• HDD OK
• HDD Plus
• HDD Repair
• HDD Rescue
• HDD Scan
• HDD Tools
• Hard Drive
• Hard Drive Diagnostic
• Memory Fixer
• Memory Scan
• Memory optimizer
• My Disk
• PC Repair
• Quick Defrag
• Quick Defragmenter
• Scan Disk
• Scanner
• Smart Defragmenter
• Smart HDD
• S.M.A.R.T. Repair
• SMART Check
• S.M.A.R.T. Check
• System Defragmenter
• System Diagnostic
• System Repair
• Ultra Defragger
• Win Defrag
• Win Defragmenter
• Win Disk
• Win HDD
• Win Scan
• Win Scanner
• Windows Diagnostic
• Windows Disk
• Windows Fix Disk
• Windows Recovery
• Windows Repair
• Windows Restore
• Windows Safemode
• Windows Scan
• Windows Tool

Some variants also use the operating system in its brand:

• Windows Fix (for example, "Windows XP Fix", "Windows Vista Fix", "Windows 7 Fix", and so on)
• Windows Recovery (for example, "Windows XP Recovery", "Windows Vista Recovery", "Windows 7 Recovery", and so on)
• Windows Repair(for example, "Windows XP Repair", "Windows Vista Repair", "Windows 7 Repair", and so on)
• Windows Restore(for example, "Windows XP Restore", "Windows Vista Restore", "Windows 7 Restore", and so on)

Installation

The Win32/FakeSysdef installer may arrive in the computer with various file names. When run, the installer drops and injects a DLL file (or sometimes and EXE file) into common processes, for example "EXPLORER.EXE", "WINLOGON.EXE", and "WININET.EXE".

In some instances, the main executable drops both DLL and EXE components. In this case, the EXE is set to run at every Windows restart and the DLL is injected into "EXPLORER.EXE" by the "EXE" component.

To ensure that it automatically runs every time Windows starts, it drops a copy of itself or its EXE component using a random file name into the %APPDATA folder.

Some variants also create shortcuts on the Desktop and in the Start Menu using the following naming format:

• %USERPROFILE%\Desktop\<FakeSysdef brand name>.lnk
• %USERPROFILE%\Start Menu\Programs\<FakeSysdef brand name>
• %USERPROFILE%\Start Menu\Programs\<FakeSysdef brand name>\<FakeSysdef brand name>.lnk
• %USERPROFILE%\Start Menu\Programs\<FakeSysdef brand name>\Uninstall <FakeSysdef brand name>.lnk

The shortcut file may look similar to the following:

The Start Menu entry may look similar to the following:

The Task Bar icon may look similar to the following:

Some variants may also create entries in the registry that allow their dropped copy to run every time Windows starts, for example:

In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Sets value: "<random string>"
With data: "%APPDATA%\<FakeSysdef copy.exe"

Win32/FakeSysdef variants also create the following registry modifications:

In subkey: HKCU\Software\Microsoft\GDIPlus
Sets value: "FontCachePath"
With data: "%APPDATA%"

In subkey: HKCU\Software\Microsoft\Internet Explorer\Main
Sets value: "Use FormSuggest"
With data: "yes"

Some variants delete the currently running FakeSysdef file after it has performed its malicious routine, as with the PC Repair variant, which drops the following file then deletes it after successful installation:

%COMMON_APPDATA%\<FakeSysdef_file name>.exe - for example, C:\Documents and Settings\All Users\Application Data\3CKFqz6zlpzK.exe

Payload

Modifies browser settings
Win32/FakeSysdef modifies several Internet Explorer settings, such as the following:

Enables submitting non-encrypted form data:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
Sets value: "1601"
With data: "0"

Changes the setting for certificates used:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing
Sets value: "State"
With data: "146944"

Enables changing the desktop wallpaper:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
Sets value: "NoChangingWallPaper"
With data: "0"

Displays all shortcuts:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
Sets value: "HideIcons"
With data: "0"

Disables Task Manager:
In subkeys:
HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System
HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System
Sets value: "DisableTaskMgr"
With data: "1"

Disables checking for signatures on downloaded programs:
In subkey: HKCU\Software\Microsoft\Internet Explorer\Download
Sets value: "CheckExeSignatures"
With data: "no"

Disables marking file attachments by using their zone information:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments
Sets value: "SaveZoneInformation"
With data: "1"

Sets low risk file types:
In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
Sets value: "LowRiskFileTypes"
With data: "/{hq:/s`s:/ogn:/uyu:/dyd:/c`u:/bnl:/ble:/sdf:/lrh:/iul:/iulm:/fhg:/clq:/kqf:/`wh:/lqf:/lqdf:/lnw:/lq2:/l2t:/v`w:/rbs:"

Terminates or blocks programs
Some Win32/FakeSysdef variants that may terminate running processes during installation and may block launched application after the computer restarts. During the installation process, they may terminate all running processes and force the computer to restart.

After the restart, FakeSysdef attempts to block every launched program, and may then display fake error messages offering to fix the problem. It then repeatedly restarts the computer until the user agrees to buy the fake software.

Displays fake warning messages
When run, Win32/FakeSysdef may display fake messages indicating that the computer has various performance and stability issues. The fake program interface may look similar to the following:

Some of the fake error messages that it displays may look similar to the following:

When the "Fix Errors" button is selected, FakeSysdef pretends to scan and defragment the hard disk. It then displays more fake error messages, and tells the user that he needs to purchase an "Advanced Module" for the fix. If the user chooses to do so, the browser opens. It will open a custom web browser where the user can input his credit card information to buy the software:

Connects to a remote server
Win32/FakeSysdef connects to certain servers to inform them that a computer has been infected. Some of the servers that Win32/Fakesysdef is known to connect to are:

• asha<removed>.com
• click<removed>.org
• beaut<removed>.com
• media<removed>.com
• search<removed>.org
• find<removed>.org

Analysis by Shawn Wang and Rex Plantado