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Backdoor.Win64.COBEACON.ZCLG

July 17, 2024
 Analysis by: Raymart Christian Yambot
 ALIASES:

Win32:Agent-BDKJ [Drp] (AVAST)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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. It connects to a website to send and receive information. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

660,480 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

25 Apr 2023

Payload:

Collects system information, Connects to URLs/IPs

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:

  • Connect and disconnect to a named pipe
  • Escalate privileges
  • Execute arbitrary commands
  • Impersonate tokens
  • Inject code into processes
  • Manage directories (Create, Remove, Set Directory)
  • Manage files (List, Create, Delete, Modify, Rename, Copy)
  • Manage processes (List, Create, Terminate)
  • List Drive Information
  • Use/purge Kerberos tickets

It connects to the following websites to send and receive information:

  • http://{BLOCKED}g-f12b.azuer.workers.dev/feedback/js/help/prod/service/lazy.min.js
  • http://{BLOCKED}g-f12b.azuer.workers.dev/we/s/h36B915845CCD42D1_App_Scripts/jquery.signalR2.1.1.min.js

However, as of this writing, the said sites are inaccessible.

Information Theft

This Backdoor gathers the following data:

  • Username
  • Computer name
  • Operating System Version
  • Executable used to load the sample

Other Details

This Backdoor requires the following additional components to properly run:

It does the following:

  • This sample needs to be located in the %windows%\assembly directory and have a file name of 'mscorsvc.dll' to execute properly.
  • It is loaded by normal file Mscorsvw.exe which is acomponent of Windows, and is otherwise known as the .NET Framework Optimization Service.
  • It requires to be executed as a service.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

19.470.04

FIRST VSAPI PATTERN DATE:

16 Jul 2024

VSAPI OPR PATTERN File:

19.471.00

VSAPI OPR PATTERN Date:

17 Jul 2024

Step 1

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 2

Identify and terminate files detected as Backdoor.Win64.COBEACON.ZCLG

[ 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 3

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win64.COBEACON.ZCLG. 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 the following Trend Micro Support pages for more information:


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