Trojan.BAT.BATCLOAK.A

 Analysis by: Jayvee Mark Villaroman

 ALIASES:

Generic.BAT.Downloader.C.7E10499D (BITDEFENDER), BAT/Agent.dp (MCAFEE)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Trojan 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. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

1,856,801 bytes

File Type:

BAT

Memory Resident:

No

Initial Samples Received Date:

15 Jun 2023

Payload:

Displays graphics/image, Encrypts files

Arrival Details

This Trojan 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 Trojan adds the following processes:

  • copy C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe /y "{File name}.exe"
  • {File Name}.exe -noprofile -ep bypass -c {encrypted command}

Other Details

This Trojan does the following:

  • It encrypts files using Rjindael (AES) encryption.
  • It displays the following screen after it finishes encrypting files:
  • It contains an encrypted payload and executes it in memory.

Ransomware Routine

This Trojan encrypts files found in the following folders:

  • %Desktop%
  • %User Profile%\Documents
  • %User Profile%\Pictures

(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).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} 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:

  • {Original filename}.{Original extension}.scytaleSECC

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

  • \___RECOVER__FILES__.scytaleSECC.txt

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.510.03

FIRST VSAPI PATTERN DATE:

15 Jun 2023

VSAPI OPR PATTERN File:

18.511.00

VSAPI OPR PATTERN Date:

16 Jun 2023

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

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.
  •  %Desktop%\\___RECOVER__FILES__.scytaleSECC.txt

Step 3

Scan your computer with your Trend Micro product to delete files detected as Trojan.BAT.BATCLOAK.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 4

Restore encrypted files from backup.


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