Analysis by: Jeffrey Francis Bonaobra

ALIASES:

Ransom:Linux/Royal.A!MTB (MICROSOFT), UDS:Trojan-Ransom.Linux.Royal.a (KASPERSKY)

 PLATFORM:

Linux

 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 drops files as ransom note.

  TECHNICAL DETAILS

File Size: 2,558,055 bytes
File Type: ELF
Memory Resident: No
Initial Samples Received Date: 02 Feb 2023
Payload: Drops 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 adds the following processes:

  • If the argument -stopvm is used:
    • /bin/sh -c esxcli vm process list > list
    • /bin/sh -c esxcli vm process kill --type=hard --world-id={World ID of the VM to terminate}

Other Details

This Ransomware accepts the following parameters:

  • required to proceed to its encryption routine:
    • {path} → directory to encrypt
    • -id {32 byte characters} → Victim ID
  • -ep {integer from 0 to 100} → used to define encryption parameter
  • -stopvm → used to terminate VM processes via ESXCLi command
  • -vmonly → used to only encrypt virtual machines
  • -fork → used to create a duplicate child process of itself
  • -logs → used to display activity logs

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • .royal_u
  • .royal_w
  • .sf
  • .v00
  • .b00
  • royal_log_
  • readme

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

  • .royal_u

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

  • {Encrypted directory}\readme

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.232.04
FIRST VSAPI PATTERN DATE: 02 Feb 2023
VSAPI OPR PATTERN File: 18.233.00
VSAPI OPR PATTERN Date: 03 Feb 2023

Step 1

Scan your computer with your Trend Micro product to delete files detected as Ransom.Linux.ROYAL.THBOBBC. 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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