Analysis by: Arianne Grace Dela Cruz

ALIASES:

Trojan:Win32/Cobaltstrike.MK!MTB (MICROSOFT); Backdoor.Cobalt (NORTON)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Canal de infección 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.

It gathers information and reports it to its servers.

  TECHNICAL DETAILS

Tamaño del archivo 289,280 bytes
Tipo de archivo EXE
Residente en memoria Yes
Fecha de recepción de las muestras iniciales 27 Sep 2020
Carga útil 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.

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):

  • added %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:

  • Upload/Download files
  • Obtain/Create access tokens
  • Impersonate tokens
  • Execute arbitrary commands
  • Manage files (Create, Delete, Move, etc)
  • Manage processes (Create, Suspend, Kill, etc)
  • Inject Code into Processes
  • Connect to a named pipe
  • Escalate Privileges
  • Enumerate registries
  • Manage Directories (Create, Remove)

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

  • https://as.{BLOCKED}ybaby.com/jp?homepage=false
  • https://af.{BLOCKED}ybaby.com/fam_cart?homepage=false
  • https://ad.{BLOCKED}ybaby.com/get?homepage=false

Other Details

This Backdoor does the following:

  • It creates a named pipe called MSSE-{Random number}-server.
  • It tries to start the following service:
    • DceRpcSs

It gathers the following information and reports it to its servers:

  • Computer Name
  • Username
  • Host Name
  • Current Process ID
  • Current OS Version
  • System Locale Information

  SOLUTION

Motor de exploración mínimo 9.850
Primer archivo de patrones de VSAPI 16.252.06
Primera fecha de publicación de patrones de VSAPI 27 Sep 2020
Versión de patrones OPR de VSAPI 16.253.00
Fecha de publicación de patrones OPR de VSAPI 28 Sep 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.XXPE50FFF036

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.COBALT.AD

[ 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.COBALT.AD. 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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