Analysis by: Kathleen Notario
 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 210,432 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 26 Nov 2010

Installation

This backdoor creates the following folders:

  • %Application Data%\{random existing folder}\{random folder name}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\MSoftware

Dropping Routine

This backdoor drops the following files:

  • %Application Data%\{random existing folder}\{random folder name}\msftcore.dat - non-malicious file
  • %Application Data%\{random existing folder}\{random folder name}\msftcore.dll - also detected as BKDR_MSFT.B
  • %Application Data%\{random existing folder}\{random folder name}\msftdm.exe - non-malicious file
  • %Application Data%\{random existing folder}\{random folder name}\msftdm32.exe - non-malicious file
  • %Application Data%\{random existing folder}\{random folder name}\msfteml.dll - also detected as BKDR_MSFT.B
  • %Application Data%\{random existing folder}\{random folder name}\msftldr.dll - also detected as BKDR_MSFT.B
  • %Application Data%\{random existing folder}\{random folder name}\msftmod.dat - non-malicious file
  • %Application Data%\{random existing folder}\{random folder name}\msftstp.exe - also detected as BKDR_MSFT.B
  • %Application Data%\{random existing folder}\{random folder name}\msfttcp.dll - also detected as BKDR_MSFT.B
  • %User Temp%\msftcore.dat - non-malicious file
  • %User Temp%\msftcore.dll - also detected as BKDR_MSFT.B
  • %User Temp%\msftdm.exe - non-malicious file
  • %User Temp%\msftdm32.exe - non-malicious file
  • %User Temp%\msfteml.dll - also detected as BKDR_MSFT.B
  • %User Temp%\msftldr.dll - also detected as BKDR_MSFT.B
  • %User Temp%\msftmod.dat - non-malicious file
  • %User Temp%\msftstp.exe - also detected as BKDR_MSFT.B
  • %User Temp%\msfttcp.dll - also detected as BKDR_MSFT.B
  • %User Startup%\WinUpdate.lnk - non-malicious file

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: currently processing

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

Scan your computer with your Trend Micro product and note files detected as BKDR_MSFT.B

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • MSoftware

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %Application Data%\{random existing folder}\{random folder name}

Step 6

Search and delete this file

[ 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.
%User Temp%\msftcore.dat
%User Temp%\msftdm.exe
%User Temp%\msftdm32.exe
%User Temp%\msftmod.dat
%User Startup%\WinUpdate.lnk

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_MSFT.B. 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.


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