ALIASES:

Rogue:Win32/Fakeinit (Microsoft); BackDoor-DKI.gen.bm (McAfee); Trojan.FakeAV!gen9 (Symantec); Trojan-Downloader.Win32.FraudLoad.gkm (Kaspersky); Trojan-Downloader.Win32.Fakeinit (v) (Sunbelt); Trojan.FakeAlert.BUA (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size: 20,480 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Nov 2012

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %System%\smss32.exe
  • %System%\winlogon32.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
smss32.exe = "%System%\smss32.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\winlogon32.exe"

(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)

Other System Modifications

This backdoor deletes the following files:

  • %Temp%\scs1.tmp
  • %Temp%\scs2.tmp
  • %Temp%\scs3.tmp
  • %Temp%\scs5.tmp
  • %Temp%\scs4.tmp
  • %Temp%\scs6.tmp
  • %Temp%\scs7.tmp
  • %Temp%\scs8.tmp
  • %Temp%\scs9.tmp
  • %Temp%\scsA.tmp
  • %Temp%\scsB.tmp
  • %Temp%\scsC.tmp
  • %Temp%\scsD.tmp
  • %Temp%\scsE.tmp
  • %Temp%\scsF.tmp
  • %Temp%\scs10.tmp
  • %Temp%\scs11.tmp
  • %Temp%\scs12.tmp
  • %Temp%\scs13.tmp
  • %Temp%\scs14.tmp
  • %Temp%\scs15.tmp
  • %Temp%\scs16.tmp
  • %Temp%\scs17.tmp
  • %Temp%\scs18.tmp
  • %Temp%\scs19.tmp
  • %Temp%\scs1A.tmp
  • %Temp%\scs1B.tmp
  • %Temp%\scs1C.tmp
  • %Temp%\scs1D.tmp
  • %Temp%\scs1E.tmp
  • %Temp%\scs1F.tmp
  • %Temp%\scs20.tmp

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop
NoChangingWallpaper = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer
NoSetActiveDesktop = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
ActiveDesktop
NoChangingWallpaper = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer
NoActiveDesktopChanges = "1"

HKEY_CURRENT_USER\Software
8636065b-fef0-4255-b14f-54639f7900a4 = "8636065b-fef0-4255-b14f-54639f7900a4"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoSetActiveDesktop = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoActiveDesktopChanges = "1"

Dropping Routine

This backdoor drops the following files:

  • %System%\helper32.dll
  • %System%\IS15.exe
  • %System%\41.exe
  • %System%\18467.exe
  • %System%\6334.exe
  • %System%\26500.exe
  • %System%\19169.exe
  • %System%\15724.exe
  • %System%\11478.exe
  • %System%\29358.exe
  • %System%\26962.exe
  • %System%\24464.exe
  • %System%\5705.exe
  • %System%\28145.exe
  • %System%\23281.exe
  • %System%\16827.exe
  • %System%\9961.exe
  • %System%\491.exe
  • %System%\2995.exe
  • %System%\11942.exe
  • %System%\4827.exe
  • %System%\smss32.exe
  • %System%\winlogon32.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}adavr50.com/loads.php?code=0001321
  • http://{BLOCKED}adavr50.com/dfghfghgfj.dll
  • http://{BLOCKED}adavr50.com/cgi-bin/download.pl?code=0001321
  • http://{BLOCKED}rdown.com/cgi-bin/get.pl?l=0001321

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and delete files detected as BKDR_SMALLDOO.MF using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware.

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • System
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • ActiveDesktop
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies
    • Explorer
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies
    • ActiveDesktop

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • smss32.exe = "%System%\smss32.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
    • NoChangingWallpaper = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer
    • NoSetActiveDesktop = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\ActiveDesktop
    • NoChangingWallpaper = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer
    • NoActiveDesktopChanges = "1"
  • In HKEY_CURRENT_USER\Software
    • 8636065b-fef0-4255-b14f-54639f7900a4 = "8636065b-fef0-4255-b14f-54639f7900a4"

Step 6

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\winlogon32.exe"
      To: Userinit = ""%Windows%\system32\userinit.exe,""

Step 7

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System%\helper32.dll
  • %System%\IS15.exe
  • %System%\41.exe
  • %System%\18467.exe
  • %System%\6334.exe
  • %System%\26500.exe
  • %System%\19169.exe
  • %System%\15724.exe
  • %System%\11478.exe
  • %System%\29358.exe
  • %System%\26962.exe
  • %System%\24464.exe
  • %System%\5705.exe
  • %System%\28145.exe
  • %System%\23281.exe
  • %System%\16827.exe
  • %System%\9961.exe
  • %System%\491.exe
  • %System%\2995.exe
  • %System%\11942.exe
  • %System%\4827.exe
  • %System%\smss32.exe
  • %System%\winlogon32.exe

Step 8

Scan your computer with your Trend Micro product to delete files detected as BKDR_SMALLDOO.MF. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 9

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Temp%\scs1.tmp
  • %Temp%\scs2.tmp
  • %Temp%\scs3.tmp
  • %Temp%\scs5.tmp
  • %Temp%\scs4.tmp
  • %Temp%\scs6.tmp
  • %Temp%\scs7.tmp
  • %Temp%\scs8.tmp
  • %Temp%\scs9.tmp
  • %Temp%\scsA.tmp
  • %Temp%\scsB.tmp
  • %Temp%\scsC.tmp
  • %Temp%\scsD.tmp
  • %Temp%\scsE.tmp
  • %Temp%\scsF.tmp
  • %Temp%\scs10.tmp
  • %Temp%\scs11.tmp
  • %Temp%\scs12.tmp
  • %Temp%\scs13.tmp
  • %Temp%\scs14.tmp
  • %Temp%\scs15.tmp
  • %Temp%\scs16.tmp
  • %Temp%\scs17.tmp
  • %Temp%\scs18.tmp
  • %Temp%\scs19.tmp
  • %Temp%\scs1A.tmp
  • %Temp%\scs1B.tmp
  • %Temp%\scs1C.tmp
  • %Temp%\scs1D.tmp
  • %Temp%\scs1E.tmp
  • %Temp%\scs1F.tmp
  • %Temp%\scs20.tmp


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