Analysis by: Joshua Paul Ignacio


Trojan.CobaltStrike.BK (BITDEFENDER), Win32:CobaltStrike-A [Trj] (AVAST)




  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel: Downloaded from the Internet, Dropped by other malware

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


File Size: 208,896 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 03 Mar 2021
Payload: Connects to URLs/IPs, Steals information

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.

Backdoor Routine

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

  • Manage Files (Create, Delete, Modify, Upload, Download, etc.)
  • Manage Directory (Create, Remove, etc.)
  • Manage Processes (Create, Open, Terminate, etc.)
  • Escalate Privileges
  • Impersonate Tokens
  • Inject Code to Processes
  • Execute Arbitrary Commands
  • Connect to a named pipe
  • List Drive Information
  • Enumerate Registries

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

  • http://{BLOCKED}.{BLOCKED}.247.115:443

Information Theft

This Backdoor gathers the following data:

  • User Name
  • Computer Name
  • Host Name
  • Local IP Address
  • OS Version and Architecture
  • Current Process ID


Minimum Scan Engine: 9.850
VSAPI OPR PATTERN File: 16.573.00
VSAPI OPR PATTERN Date: 04 Mar 2021

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • Troj.Win32.TRX.XXPE50FFF042

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

Identify and terminate files detected as Backdoor.Win32.COBEACON.THCOCBA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.COBEACON.THCOCBA. 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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