Analysis by: Paul Steven Nadera
ALIASES:

a variant of Win32/Filecoder.ODE trojan (NOD32);

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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: 43,008 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 01 Dec 2020

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:

  • %AppDataLocal%\{generated extension}.ico

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Ransomware adds the following registry entries:

HKLM\SOFTWARE\Classes\
.{generated extension}
(Default) = {generated extension}

HKLM\SOFTWARE\Classes\
{generated extension}\DefaultIcon
(Default) = %AppDataLocal%\{generated extension}.ico

Other Details

This Ransomware adds the following registry keys:

HKLM\SOFTWARE\Classes\
.{generated extension}

HKLM\SOFTWARE\Classes\
{generated extension}

HKLM\SOFTWARE\Classes\
{generated extension}\DefaultIcon

It connects to the following possibly malicious URL:

  • https://{BLOCKED}app20.com/{random characters}

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .{generated extension}

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

  • {Encrypted Directory}\README.{generated extension}.txt

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.388.06
FIRST VSAPI PATTERN DATE: 02 Dec 2020
VSAPI OPR PATTERN File: 16.389.00
VSAPI OPR PATTERN Date: 03 Dec 2020

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.XXPE50FFF038

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

Identify and terminate files detected as Ransom.Win32.DARKSIDE.YXAL-A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 5

Delete this registry key

[ 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.

  • HKLM\SOFTWARE\Classes\.{generated extension}HKLM\SOFTWARE\Classes\{generated extension}HKLM\SOFTWARE\Classes\{generated extension}\DefaultIcon

Step 6

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.

    • HKLM\SOFTWARE\Classes\.{generated extension}
    • (Default) = {generated extension}
    • HKLM\SOFTWARE\Classes\{generated extension}\DefaultIcon
    • (Default) = %AppDataLocal%\{generated extension}.ico

Step 7

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 Directory}\README.{generated extension}.txt
  • %AppDataLocal%\{generated extension}.ico

Step 8

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.DARKSIDE.YXAL-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 9

Restore encrypted files from backup.


Did this description help? Tell us how we did.