Ransom.Linux.HELLOKITTY.YXBHM

October 14, 2021
 Analysis by: Bren Matthew Ebriega
 ALIASES:

Linux/Hellokit!tr (FORTINET)

 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 encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

57,536 bytes

File Type:

ELF

Memory Resident:

Yes

Initial Samples Received Date:

13 Aug 2021

Payload:

Drops files, Displays graphics/image, 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 drops the following files:

  • {Malware Folder}/work.log → Contains log of actions done.

It adds the following processes:

  • If ran with the argument -k:
    • esxcli vm process list
    • esxcli vm process kill -t=soft -w={id}
    • esxcli vm process kill -t=hard -w={id}
    • esxcli vm process kill -t=force -w={id}

Other Details

This Ransomware accepts the following parameters:

  • -v - Enable Verbose Logging.
  • -d - Run as Daemon.
  • -k - Kill running EXSi VM.
  • -e - Encrypt VM files.
  • {Starting Folder} - Starting Directory to Encrypt.
  • -m (10-20-25-33-50)

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • If ran with the argument -e:
    • .vmdk
    • .vmx
    • .vmsd
    • .vmsn

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

  • .crypt
  • .README_TO_RESTORE
  • .tmp_
  • If not ran with the argument -e:
    • .a
    • .so
    • .la
    • .xxx

It avoids encrypting files with the following strings in their file path:

  • /bin
  • /boot
  • /dev
  • /etc
  • /lib
  • /lib32
  • /lib64
  • /lost+found
  • /proc
  • /run
  • /sbin
  • /usr/bin
  • /usr/include
  • /usr/lib
  • /usr/lib32
  • /usr/lib64
  • /usr/sbin
  • /sys
  • /usr/libexec
  • /usr/share
  • /var/lib

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

  • .crypt

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

  • {Encrypted Folder}/{Original Filename}.{Original File Extension}.tmp_.README_TO_RESTORE

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.128.02

FIRST VSAPI PATTERN DATE:

13 Oct 2021

VSAPI OPR PATTERN File:

17.129.00

VSAPI OPR PATTERN Date:

14 Oct 2021

Step 1

Scan your computer with your Trend Micro product to delete files detected as Ransom.Linux.HELLOKITTY.YXBHM. 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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