BKDR_TURLA.YLH


 PLATFORM:

Windows

 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.

  TECHNICAL DETAILS

File Size:

664,576 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Apr 2017

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 creates the following folders:

  • %Program Files%\Windows Media Player\Sample Playlists\System
  • %Program Files%\Windows Media Player\Sample Playlists\Nls
  • %Program Files%\Windows Media Player\Sample Playlists\0208

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

Autostart Technique

This Backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ipvpn\Parameters

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ipvpn\Parameters
ServiceDLL = "%SystemRoot%\system32\ipvpn.dll"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ipvpn\Parameters
ServiceDllUnloadOnStop = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\ipvpn\Parameters
ServiceMain = "ServiceMain"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = "{random characters}"

(Note: The default value data of the said registry entry is {random values}.)

Dropping Routine

This Backdoor drops the following files:

  • %Program Files%\Windows Media Player\Sample Playlists\miniport.dat
  • %Program Files%\Windows Media Player\Sample Playlists\msimghlp.dll
  • %Program Files%\Windows Media Player\Sample Playlists\msximl.dll
  • %System%\ipvpn.dll
  • %User Profile%\RSA\S-1-5-18

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.8

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ipvpn
    • Parameters

Step 4

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\SYSTEM\ControlSet001\Services\ipvpn\Parameters
    • ServiceDLL = "%SystemRoot%\system32\ipvpn.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\ipvpn\Parameters
    • ServiceDllUnloadOnStop = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\ipvpn\Parameters
    • ServiceMain = "ServiceMain"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = "{random characters}"
      To: netsvcs = ""{random values}""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %Program Files%\Windows Media Player\Sample Playlists\miniport.dat
  • %Program Files%\Windows Media Player\Sample Playlists\msimghlp.dll
  • %Program Files%\Windows Media Player\Sample Playlists\msximl.dll
  • %System%\ipvpn.dll
  • %User Profile%\RSA\S-1-5-18

Step 7

Search and delete these folders

[ 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.
  • %Program Files%\Windows Media Player\Sample Playlists\System
  • %Program Files%\Windows Media Player\Sample Playlists\Nls
  • %Program Files%\Windows Media Player\Sample Playlists\0208

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_TURLA.YLH. 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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