Ransom.Win64.TRIGONA.B


 ALIASES:

Ransom:Win32/Filecoder.AA!MTB (MICROSOFT)

 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, 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:

498,688 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

13 Dec 2023

Payload:

Deletes files, Modifies system registry, Collects system information, Encrypts files, 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 adds the following processes:

  • %System%\cmd.exe /c\"bcdedit /set{default} recoveryenabled No\"
  • %System%\cmd.exe /c\"bcdedit /set {default} bootstatuspolicy ignoreallfailures\"
  • %System%\cmd.exe /c\"wbadmin DELETE BACKUP -keepVersions:0\"
  • %System%\cmd.exe /c\"wbadmin DELETE SYSTEMSTATEBACKUP -keepVersions:0\"
  • %System%\cmd.exe /c\"wmic SHADOWCOPY DELETE\"
  • %System%\cmd.exe /c\"vssadmin delete shadows /all /quiet\"
  • %System%\mshta.exe %User Temp%\how_to_decrypt.hta

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {Generated ID} → Derived from computer name and creation time of %Windows%

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

Information Theft

This Ransomware gathers the following data:

  • Computer Name
  • Username
  • OS Version
  • System Locale
  • Keyboard Layout
  • Disk Data
  • Network Configuration Information

Other Details

This Ransomware does the following:

  • By default, It encrypt local drives and network drives
  • It displays its ransom note after encryption
  • It loads its configuration found in its resource section named CFGS.
  • It checks for the presence of the following file that serves as its configuration file:
    • cfgs.txt
  • It encrypts the information it gathers and stores it in the authentication key required during the negotiation procedures to retrieve files
  • It can terminate processes and services based on the configuration.

It accepts the following parameters:

  • /r → encrypt files in random order
  • /sleep → sleep for n seconds before execution
  • /full → encrypt the whole contents of a file (by default, only the first 0x80000 bytes/512kb are encrypted)
  • /debug → execute in debug mode, need to be executed with /p
  • /log_f → for logging, specify the log file
  • /fast
  • /erase → delete contents of a file
  • /is_testing → for testing purposes, used with /test_cid and /test_vid
  • /test_cid → Use the specified value instead of generating a computer ID
  • /test_vid → Use the specified value instead of the hardcoded victim ID (VID) from the configuration
  • /p → specify path to encrypt
  • /path → specify path to encrypt
  • /!local → Do not encrypt local files
  • /!lan → Do not encrypt network shares
  • /shdwn → Turn off the machine after encryption using the parameter -f -s -t 00
  • /allow_system → Allows encrypting files in system directory
  • /!clear_shadow → Do not delete shadow copies
  • /wipe
  • /block
  • /step
  • /band_start
  • /!prerename → Do not rename files before encryption
  • /delete → Deletes itself after execution
  • /priority → Sets encryption priority
  • /clear_exclude
  • /ips
  • /stealth → Do not rename encrypted files, needs to be executed with /p
  • /e

Ransomware Routine

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

  • how_to_decrypt.hta
  • how_to_decrypt.txt
  • NTUSER.DAT

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

  • windows
  • system32

It renames encrypted files using the following names:

  • available_for_trial.{random}._locked
  • {random}._locked

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

  • %User Temp%\how_to_decrypt.hta
  • {Encrypted Directory}\how_to_decrypt.hta

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.882.02

FIRST VSAPI PATTERN DATE:

16 Dec 2023

VSAPI OPR PATTERN File:

18.883.00

VSAPI OPR PATTERN Date:

17 Dec 2023

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:

    • Troj.Win32.TRX.XXPE50FFF075

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

Search and delete these files

[ 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.
  • %User Temp%\how_to_decrypt.hta
  • {Encrypted directory}\ how_to_decrypt.hta

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.TRIGONA.B. 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:


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