BKDR_SERKDES.C

January 26, 2018
 Analysis by: John Anthony Banes
 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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 does not have any propagation routine.

It executes commands from a remote malicious user, effectively compromising the affected system.

It gathers information and reports it to its servers.

  TECHNICAL DETAILS

File Size:

163,328 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

23 Jan 2017

Payload:

Connects to URLs/IPs, Steals information, Executes files, Compromises system security

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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • V1.0

Autostart Technique

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

HKEY_CURRENT_USER\Software\Classes\
CLSID\{ECD4FC4D-521C-11D0-B792-00A0C90312E1}\InProcServer32
(Default) = {Malware Path and Filename}

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Classes\
CLSID\{ECD4FC4D-521C-11D0-B792-00A0C90312E1}\InProcServer32
ThreadingModel = Apartment

HKEY_CURRENT_USER\Software\Classes\
Folder\shellex\ContextMenuHandlers\
Microsoft
(Default) = {GUID}

HKEY_CURRENT_USER\Software\Classes\
Folder\shellex\DragDropHandlers\
Microsoft
(Default) = {GUID}

HKEY_CURRENT_USER\Software\Classes\
Folder\shellex\PropertySheetHandlers\
Microsoft
(Default) = {GUID}

HKEY_CURRENT_USER\Software\Classes\
*\shellex\PropertySheetHandlers\
Microsoft
(Default) = {GUID}

HKEY_CURRENT_USER\Software\Classes\
*\shellex\DragDropHandlers\
Microsoft
(Default) = {GUID}

Propagation

This Backdoor does not have any propagation routine.

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Update server config file (%Temp%\sysconf)
  • Download/Upload arbitrary files from/to the C&C
  • Create/Delete Arbitrary Files
  • Take a screenshot
  • List Drives, Files and Folders
  • Execute arbitrary files/codes
  • Terminate Processes
  • Move mouse Cursor
  • Simulate key presses

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.{BLOCKED}.26.126:443

Other Details

This Backdoor does the following:

  • The C&C, proxy server, port number, and the credentials for the proxy depend on the config file %Temp%\sysconf. If the said file is not present, it uses the default settings. By default, this backdoor may use proxy connections.

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

It gathers the following information and reports it to its servers:

  • Host name
  • User name
  • MAC address
  • System Default Language
  • System Type (32-bit or 64-bit)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.922.03

FIRST VSAPI PATTERN DATE:

23 Jan 2018

VSAPI OPR PATTERN File:

13.923.00

VSAPI OPR PATTERN Date:

24 Jan 2018

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Classes\CLSID\{ECD4FC4D-521C-11D0-B792-00A0C90312E1}\InProcServer32
    • (Default) = {Malware Path and Filename}
  • In HKEY_CURRENT_USER\Software\Classes\CLSID\{ECD4FC4D-521C-11D0-B792-00A0C90312E1}\InProcServer32
    • ThreadingModel = Apartment
  • In HKEY_CURRENT_USER\Software\Classes\Folder\shellex\ContextMenuHandlers\Microsoft
    • (Default) = {GUID}
  • In HKEY_CURRENT_USER\Software\Classes\Folder\shellex\DragDropHandlers\Microsoft
    • (Default) = {GUID}
  • In HKEY_CURRENT_USER\Software\Classes\Folder\shellex\PropertySheetHandlers\Microsoft
    • (Default) = {GUID}
  • In HKEY_CURRENT_USER\Software\Classes\*\shellex\PropertySheetHandlers\Microsoft
    • (Default) = {GUID}
  • In HKEY_CURRENT_USER\Software\Classes\*\shellex\DragDropHandlers\Microsoft
    • (Default) = {GUID}

Step 5

Search and delete these files

[ Learn More ]
There may be some 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.
  • %Temp%\sysconf

Step 6

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


Did this description help? Tell us how we did.