Analysis by: Mc Justine De Guzman
ALIASES:

Backdoor.Cobalt (NORTON)

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

  TECHNICAL DETAILS

File Size: 289,280 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Feb 2021
Payload: Collects system information, Modifies files, Executes files, Enumerates registries, directory, and files

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

(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
    • Adjust Privileges

Information Theft

This Backdoor gathers the following data:

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

Other Details

This Backdoor does the following:

  • It creates an outbound pipe named:
    • MSSE-{Random Number}-server
  • It creates a bi-directional pipe named:
    • wkssvc_ced
  • It waits for a connection in the created bi-directional pipe to execute arbitrary code
  • It starts the following service:
    • DceRpcSs
  • It will only proceed to its malicious routine if it is ran as a service

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.262.04
FIRST VSAPI PATTERN DATE: 02 Oct 2020
VSAPI OPR PATTERN File: 16.263.00
VSAPI OPR PATTERN Date: 03 Oct 2020

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.XXPE50FLM011

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

Disable this malware service

[ Learn More ]
    • DceRpcSs

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win64.COBEACON.SMA. 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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