Ransom.Linux.BRAINCIPHER.THHOIBD

 Analysis by: Neljorn Nathaniel Aguas

 ALIASES:

Ransom:Linux/Babuk.B!MTB (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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 encrypts files with specific file extensions. It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

71,784 bytes

File Type:

ELF

Memory Resident:

No

Initial Samples Received Date:

09 Aug 2024

Payload:

Encrypts files, Displays terminal

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 drops the following files:

  • If parameter -onvm {ID1, ID2, ID3, ...} is used:
    • /tmp/running_vms.txt → contains active VM IDs retrieved from the system.

It adds the following processes:

  • If parameter -onvm {ID1, ID2, ID3, ...} is used:
    • vim-cmd vmsvc/getallvms | grep '^[0-9]' | awk '{print $1}' > /tmp/running_vms.txt → retrieves information about all VMs on an ESXi host and stores the IDs in a text file.
    • vim-cmd vmsvc/power.getstate {VM ID} | grep 'Powered on' → checks the power state of VMs on an ESXi host based on the VM IDs specified in the parameter.
    • vim-cmd vmsvc/power.off {VM ID} → powers off VMs on an ESXi host if found running.
    • rm /tmp/running_vms.txt → permanently deletes the text file.

Other Details

This Ransomware does the following:

  • It displays the following output in the terminal:

It accepts the following parameters:

  • -onvm {ID1, ID2, ID3, ...} → used to power off ESXi VMs based on IDs
  • -time {seconds} → delay in seconds before doing encryption
  • {Path to Encrypt} → directory to encrypt including subdirectories

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .log
  • .vmdk
  • .vmem
  • .vswp
  • .vmsn
  • Any files with the above strings found in their filename except with the blacklisted extensions.

It appends the following extension to the file name of the encrypted files:

  • .encrptd

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

  • {Encrypted Path}/How To Restore Your Files.txt

It avoids encrypting files with the following file extensions:

  • .encrptd
  • .encrptd{Any String}

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

19.518.02

FIRST VSAPI PATTERN DATE:

09 Aug 2024

VSAPI OPR PATTERN File:

19.519.00

VSAPI OPR PATTERN Date:

10 Aug 2024

Step 1

Scan your computer with your Trend Micro product to delete files detected as Ransom.Linux.BRAINCIPHER.THHOIBD. 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:

Step 2

Restore encrypted files from backup.


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