Backdoor.Win64.COBEACON.YXDDY

April 26, 2023
 Analysis by: Arianne Grace Dela Cruz
 ALIASES:

Trojan:Win32/Cobaltstrike!MSR (MICROSOFT); UDS:DangerousObject.Multi.Generic (KASPERSKY)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

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

It gathers certain information on the affected computer.

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

  TECHNICAL DETAILS

File Size:

109,056 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

25 Apr 2023

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 injects codes into the following process(es):

  • %System%\winlogon.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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)

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

  • http://{BLOCKED}.{BLOCKED}updates.com/css/jquery.min.js
  • http://{BLOCKED}.{BLOCKED}updates.com/index/rss.php

Information Theft

This Backdoor gathers the following information on the affected computer:

  • Username
  • Computer name
  • Current process ID
  • Operating system version and Architecture

Other Details

This Backdoor does the following:

  • It connects to the following URL to download an encyrpted component loaded in its memory to perform additional routines:
    • https://{BLOCKED}.{BLOCKED}.ge:443/wp-content/stuff/winlogon.bin

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

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.408.03

FIRST VSAPI PATTERN DATE:

26 Apr 2023

VSAPI OPR PATTERN File:

18.409.00

VSAPI OPR PATTERN Date:

27 Apr 2023

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.YXDDY

[ 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.YXDDY. 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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