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Ransom.MSIL.IMMALOCKER.A

March 19, 2024
 Analysis by: Francesca Villasanta
 ALIASES:

UDS:Trojan-Ransom.Win32.Generic (KASPERSKY); Trojan:MSIL/FileCoder.ARA!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 drops files as ransom note.

  TECHNICAL DETAILS

File Size:

123,392 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Mar 2024

Payload:

Drops files, Encrypts files, Modifies system registry, Terminates processes

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:

  • C:\LockBIT\systemID → contains the UniqueID

It adds the following processes:

  • "sc" config "{Service Name}" start= demand
    Services that contains any of the following strings in its name:
    • SQL
    • 1C:
    • IAS
    • AnyDesk
    • VSS
    • firebird
    • Acronis

It creates the following folders:

  • C:\LockBIT → with HIDDEN attribute

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
taskhostw = {Malware Path}\{Malware Path}

Process Termination

This Ransomware terminates processes or services that contain any of the following strings if found running in the affected system's memory:

  • SQL
  • 1C:
  • IAS
  • AnyDesk
  • VSS
  • firebird
  • Acronis

Other Details

This Ransomware does the following:

  • Sets the attribute of the executed sample file to HIDDEN.
  • It empties the Recycle Bin.
  • It compares a file's size against this value: 6,710,886,400 bytes.
    • Size is greater:
      File will be encrypted in CBC cipher mode
    • Size is lesser:
      Fill will be encrypted in ECB cipher mode

Ransomware Routine

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

  • .exe
  • .msi
  • .ImmaLocker
  • .dll
  • Readme

It avoids encrypting files found in the following folders:

  • C:\Windows

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

  • {Original filename}.{Original extension}.{BLOCKED}@cyberfear.com.{Unique ID}.ImmaLocker

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

  • {Encrypted Drive}:\Readme.txt
    If filename already exists, the following will be dropped instead:
    • Readme-{random}.txt
  • %Desktop%\Readme.txt
    If filename already exists, the following will be dropped instead:
    • Readme-{random}.txt

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

19.222.04

FIRST VSAPI PATTERN DATE:

17 Mar 2024

VSAPI OPR PATTERN File:

19.223.00

VSAPI OPR PATTERN Date:

18 Mar 2024

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:

     WORM.Win32.TRX.XXPE50FFF078

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

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • taskhostw = {Malware Path}\{Malware Path}

Step 5

Search and delete this file

[ 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.
  • {Encrypted Drive}:\Readme.txt
  • {Encrypted Drive}:\Readme-{random}.txt
  • %Desktop%\Readme.txt
  • %Desktop%\Readme-{random}.txt
  • C:\LockBIT\systemID

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • C:\LockBIT

Step 7

Scan your computer with your Trend Micro product to delete files detected as Ransom.MSIL.IMMALOCKER.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:

Step 8

Restore encrypted files from backup.


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