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Ransom.MSIL.BLACKCLAW.A

June 08, 2020
 Analysis by: Patrick Noel Collado
 ALIASES:

Ransom:MSIL/BlackClaw.DEA!MTB (Microsoft), HEUR:Trojan-Ransom.MSIL.Gen.gen (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

This Ransomware 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 then deletes itself afterward.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

162,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Jun 2020

Payload:

Connects to URLs/IPs, Displays message/message boxes, Encrypts files

Arrival Details

This Ransomware 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 Ransomware executes then deletes itself afterward.

Other Details

This Ransomware connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.181.154:443

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • If the generated public key's length is not greater than 10:
    • .[{Public Key}].bclaw
  • If the generated public key's length is greater than 10:
    • .bclaw

It drops the following file(s) as ransom note:

  • {Path of Encrypted File}\RECOVER YOUR FILES.txt
  • {Path of Encrypted File}\RECOVER YOUR FILES.hta

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.913.00

FIRST VSAPI PATTERN DATE:

05 Jun 2020

VSAPI OPR PATTERN File:

15.914.00

VSAPI OPR PATTERN Date:

06 Jun 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.XXPE50FFF035

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

Identify and terminate files detected as Ransom.MSIL.BLACKCLAW.A

[ 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 5

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • {Path of Encrypted File}\RECOVER YOUR FILES.txt
  • {Path of Encrypted File}\RECOVER YOUR FILES.hta

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.MSIL.BLACKCLAW.A. 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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