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Backdoor.Win64.COBEACON.OSLJEL

November 29, 2022
 Analysis by: Francesca Villasanta
 ALIASES:

Backdoor:Win64/CobaltStrike.NP!dha (MICROSOFT) ; HEUR:Trojan.Win64.CobaltStrike.gen (KASPERSKY)

 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:

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

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

288,256 bytes

File Type:

EXE

Memory Resident:

No

Payload:

Connects to URLs/IPs, Steals information, Injects code, Modifies system registry, Creates a pipe

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 processes:

  • %System%\rundll32.exe
  • %System%\cmd.exe /c "powershell -nop -exec bypass -{EncodedCommand}"

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

It injects codes into the following process(es):

  • Created %System%\rundll32.exe process

(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:

  • List Drive Information
  • Inject Code to Processes
  • Impersonate User Tokens
  • Enumerate Registries
  • Execute Arbitrary Commands
  • Manage Files:
    • Copy
    • Move
    • List
    • Open
    • Delete
    • Read/Modify file contents
    • Read/Modify file time
  • Manage Directory:
    • Create
    • Delete
  • Manage Processes:
    • Create
    • Terminate
    • Open
    • Elevation
  • Use/purge Kerberos tickets
  • Toggle SMB mode to communicate to a parent beacon via named pipes
  • Connect and disconnect to a named pipe
  • Upload/download files

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

  • http://{BLOCKED}.{BLOCKED}.196.27:10048/en_US/all.js

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

Rootkit Capabilities

This Backdoor does not have rootkit capabilities.

Information Theft

This Backdoor gathers the following information on the affected computer:

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

Other Details

This Backdoor does the following:

  • Creates the following named pipe and connects to it:
    • MSSE-{Random number}-server

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

17.958.02

FIRST VSAPI PATTERN DATE:

25 Nov 2022

VSAPI OPR PATTERN File:

17.959.00

VSAPI OPR PATTERN Date:

26 Nov 2022

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.XXPE50FFF062

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

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

[ 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 4

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win64.COBEACON.OSLJEL. 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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