Ransom.MSIL.IRANSOM.THGAEAI

August 14, 2019
 Analysis by: Jay Bradley Nebre
 Modified by: Jay Bradley Nebre
 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

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 encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

2,840,064 bytes

File Type:

EXE

File Compression:

Engima Protector

Memory Resident:

Yes

Initial Samples Received Date:

26 Jul 2019

Payload:

Displays message/message boxes, 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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
iRansom = "{malware path and file name}"

Other Details

This Ransomware displays the following message boxes:

This acts as the ransom note:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %Desktop%

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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

  • .Locked

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.258.02

FIRST VSAPI PATTERN DATE:

26 Jul 2019

VSAPI OPR PATTERN File:

15.259.00

VSAPI OPR PATTERN Date:

27 Jul 2019

Step 1

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 2

Restart in Safe Mode

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • iRansom = "{malware path and file name}"

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.MSIL.IRANSOM.THGAEAI. 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 this Knowledge Base page for more information.

Step 5

Restore encrypted files from backup.


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