Analysis by: Neljorn Nathaniel Aguas
ALIASES:

Ransom:Linux/Interlock.A (MICROSOFT)

 PLATFORM:

FreeBSD

 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: Dropped by other malware, 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 drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 808,240 bytes
File Type: ELF
Memory Resident: No
Initial Samples Received Date: 10 Oct 2024
Payload: 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.

Other Details

This Ransomware accepts the following parameters:

  • -d | --directory → encrypts a specified directory including its subdirectories
  • -f | --file → encrypts a specified file
  • -del | --delete → encrypts files then deletes itself using unlink() system call
  • -s | --system

Ransomware Routine

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

  • {Any String}boot.cfg
  • {Any String}!__README__!.txt

It avoids encrypting files found in the following folders:

  • bin
  • boot
  • cdrom
  • dev
  • etc
  • home
  • lib
  • lib32
  • lib64
  • libx32
  • lost+found
  • media
  • mnt
  • opt
  • proc
  • root
  • run
  • sbin
  • snap
  • srv
  • sys
  • tmp
  • usr
  • var

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

  • .interlock

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

  • {Encrypted Path}/!__README__!.txt

It avoids encrypting files with the following file extensions:

  • .b00
  • .sf
  • .t00
  • .v00
  • .v01
  • .v02
  • .v03
  • .v04
  • .v05
  • .v06
  • .v07
  • .interlock

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.700.06
FIRST VSAPI PATTERN DATE: 07 Nov 2024
VSAPI OPR PATTERN File: 19.701.00
VSAPI OPR PATTERN Date: 08 Nov 2024

Step 1

Scan your computer with your Trend Micro product to delete files detected as Ransom.FreeBSD.INTERLOCK.THJBBBD. 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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