DarkMystic (BlackBit) Ransomware: Analysis & Removal Guide

DarkMystic is a newly discovered variant of the BlackBit ransomware family that encrypts files, appends them with a “.darkmystic” extension, and demands Bitcoin payment for decryption. First identified on April 14, 2025, this ransomware prepends encrypted filenames with the attackers’ email address and a unique victim ID. Once encryption is complete, it changes the desktop wallpaper and creates two ransom notes: “info.hta” (pop-up) and “Restore-My-Files.txt” (text file). This comprehensive analysis examines DarkMystic’s technical aspects, operational methods, detection indicators, and provides detailed removal instructions and preventative measures to help victims recover from attacks and protect systems from future infections.

Technical Analysis of DarkMystic (BlackBit) Ransomware

DarkMystic ransomware was first identified by security researchers in April 2025 through submissions to the VirusTotal platform. This malware is a variant of the BlackBit ransomware family, which uses sophisticated encryption techniques to render victims’ files inaccessible and then demands payment for recovery. Initial technical analysis reveals that DarkMystic employs a hybrid encryption approach, using a combination of symmetric (AES-256) and asymmetric (RSA-2048) algorithms to encrypt files, making decryption without the attackers’ private key virtually impossible.

When DarkMystic infects a system, it follows a systematic encryption process that targets a wide range of file types, prioritizing documents, images, databases, and other valuable user data. The distinctive file modification pattern includes prepending the encrypted filename with the attackers’ contact information (“[darkmystic@onionmail.com][UNIQUE_ID]”) and appending the “.darkmystic” extension. For example, a file originally named “document.docx” would appear as “[darkmystic@onionmail.com][9ECFA84E]document.docx.darkmystic” after encryption.

Security researchers have determined that the ransomware employs several advanced techniques to ensure maximum effectiveness:

• Shadow Copy Deletion: Executes commands to remove Windows Volume Shadow Copies, preventing easy file restoration
• System Modification: Changes desktop wallpaper to display ransom instructions and creates persistent pop-up messages
• Multiple Communication Channels: Provides several contact methods (email addresses and Telegram) to ensure victims can reach attackers
• Escalation Strategy: Implements a doubling of the ransom amount after 48 hours to create urgency
• Targeted Encryption: Intentionally avoids encrypting system files to ensure the computer remains operational for ransom payment

Ransom Notes Analysis

DarkMystic ransomware creates two distinct ransom notes to maximize visibility and victim engagement. The first note, “info.hta,” appears as a pop-up window immediately after encryption is complete. This HTML Application file contains detailed payment instructions and communicates the attackers’ demands with a sense of urgency. The second note, “Restore-My-Files.txt,” is placed in multiple locations throughout the infected system to ensure the victim sees the instructions even if they close the pop-up window.

The ransom notes contain several key components that reveal the attackers’ methodology:

1. Deadline Structure: Establishes a 48-hour window before doubling the ransom and a final deadline after which files will allegedly be deleted
2. Demonstration Offer: Proposes to decrypt three files for free as proof of decryption capability (limited to non-system files under 5MB)
3. Payment Instructions: Detailed steps for purchasing Bitcoin and transferring it to the attackers’ wallet
4. Warnings Against Recovery Attempts: Explicit cautions against using third-party recovery tools, claiming they may permanently damage encrypted files
5. Contact Information: Multiple communication channels including email addresses (darkmystic@onionmail.com, darkmystic@tutamail.com) and Telegram (@DarkMystic_support)

ATTENTION!

Your files have been encrypted with a strong algorithm.
To recover your files, you need to purchase our decryption tool.

Price: 0.15 BTC
If you do not pay within 48 hours, the price will increase to 0.3 BTC.
After [DATE], your files will be permanently deleted.

Contact us for payment instructions:
darkmystic@onionmail.com
darkmystic@tutamail.com
Telegram: @DarkMystic_support

Your personal ID: 9ECFA84E

DO NOT attempt to decrypt files using third-party software - this will permanently damage your files.

File Encryption Process

DarkMystic employs a sophisticated encryption methodology that makes decryption without the attackers’ key mathematically infeasible. The ransomware scans the victim’s system for files with specific extensions, focusing on valuable user data while intentionally avoiding critical system files to keep the computer operational. Each file is encrypted using a unique AES-256 key, which is then encrypted with an RSA-2048 public key. Only the attackers possess the corresponding private key required for decryption.

The encryption targets over 200 file types, including but not limited to:

The ransomware specifically avoids encrypting files in certain system directories to ensure the computer remains functional:

• Windows system folders
• Program Files directories
• Boot-related files
• Browser executables

Detection Indicators: Identifying DarkMystic Infection

Identifying a DarkMystic ransomware infection is relatively straightforward due to its distinctive symptoms. The most obvious indicators are the changed desktop wallpaper displaying the ransom message and the appearance of the ransom notes. Additionally, victims will notice that their files have been renamed and appended with the “.darkmystic” extension, making them inaccessible with normal applications.

Other key infection indicators include:

• File Access Issues: Inability to open previously accessible files, with applications reporting that files are damaged or in an unknown format
• Modified Filenames: Files renamed with the pattern “[darkmystic@onionmail.com][UNIQUE_ID]filename.extension.darkmystic”
• Ransom Pop-up: The “info.hta” file repeatedly launching a pop-up window with ransom demands
• Changed Desktop Background: Desktop wallpaper replaced with ransom payment instructions
• Unusual System Activity: System slowdowns during the encryption process and increased disk activity
• Multiple Ransom Note Files: Presence of “Restore-My-Files.txt” in various folders across the system
• Deletion of Shadow Copies: Windows Volume Shadow Copies removed, preventing easy file restoration

Security software may detect DarkMystic under various detection names, including:

• Avast: Win32:MalwareX-gen [Ransom]
• ESET-NOD32: A Variant Of MSIL/Filecoder.LokiLocker.D
• Kaspersky: UDS:DangerousObject.Multi.Generic
• Microsoft: Trojan:Win32/ClipBanker.MR!MTB

Distribution Methods and Infection Vectors

DarkMystic ransomware is primarily distributed through phishing and social engineering tactics. The attackers employ various methods to trick victims into executing the malicious payload, often disguising it as legitimate content. Understanding these infection vectors is crucial for preventing future attacks and implementing effective security measures.

Common distribution methods for DarkMystic include:

1. Phishing Emails: Messages containing malicious attachments or links, often disguised as invoices, delivery notifications, or financial documents
2. Malicious Macros: Office documents with embedded macros that, when enabled, download and execute the ransomware
3. Drive-by Downloads: Compromised websites that exploit browser vulnerabilities to automatically download malware without user consent
4. Trojan Horse Programs: Malware disguised as legitimate software that, once installed, delivers the ransomware payload
5. Exploit Kits: Tools that exploit known vulnerabilities in outdated software to deliver the ransomware
6. Remote Desktop Protocol (RDP) Attacks: Brute force attacks against systems with exposed RDP services to gain unauthorized access and manually deploy the ransomware
7. Malvertising: Malicious advertisements that redirect users to compromised websites hosting the ransomware

Security researchers have noted that DarkMystic’s operators often target specific organizations or industries rather than conducting mass, indiscriminate campaigns. This targeted approach allows the attackers to customize their social engineering tactics and ransom demands based on the victim’s perceived ability to pay.

DarkMystic Ransomware Removal Instructions

Removing DarkMystic ransomware from an infected system is a multi-step process that requires careful execution. While removal will not recover encrypted files, it is essential to eliminate the malware to prevent further damage and ensure the system is secure before attempting any recovery methods. The following step-by-step guide will help you safely remove DarkMystic from your computer.

Step 1: Boot into Safe Mode with Networking

Starting your computer in Safe Mode with Networking will help prevent the ransomware from running during the cleanup process:

1. Restart your computer
2. During startup, press the F8 key repeatedly until the Advanced Boot Options menu appears
3. Select “Safe Mode with Networking” using the arrow keys
4. Press Enter to boot into Safe Mode

For Windows 10/11 users:

1. Click on Start > Settings > Update & Security > Recovery
2. Under Advanced startup, click “Restart now”
3. After restarting, select Troubleshoot > Advanced options > Startup Settings > Restart
4. Press 5 or F5 for “Safe Mode with Networking”

Step 2: Scan and Remove Malware

Use a reliable anti-malware solution to detect and remove the DarkMystic ransomware:

1. Download and install Trojan Killer from a clean device and transfer it to the infected computer using a USB drive
2. Run the installation and follow the on-screen instructions
3. Launch Trojan Killer and perform a “Deep Scan” of your system
4. When the scan completes, review the detected threats, ensuring that all components of DarkMystic are selected for removal
5. Click “Remove Selected” to eliminate the ransomware
6. Restart your computer when prompted

Step 3: Remove Ransom Notes and Restore Desktop

After removing the ransomware, you’ll need to clean up the ransom notes and reset your desktop:

1. Delete all copies of “info.hta” and “Restore-My-Files.txt” from your computer
2. Right-click on your desktop and select “Personalize”
3. Choose a new desktop background to replace the ransom message
4. Check the Startup folder (Windows+R, type “shell:startup”, click OK) and remove any suspicious items

Step 4: Remove Registry Entries

Cleaning the Windows Registry will help ensure all traces of DarkMystic are removed:

1. Press Windows+R, type “regedit”, and press Enter to open Registry Editor
2. Navigate to these locations and delete any suspicious entries (particularly those with random or unusual names):
3. HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
4. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
5. HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\StartupApproved\Run
6. Close Registry Editor when finished

File Recovery Options

Recovering files encrypted by DarkMystic ransomware is challenging, as the encryption is cryptographically strong and designed to be unbreakable without the decryption key held by the attackers. While paying the ransom may seem like the easiest solution, it is strongly discouraged as it funds criminal activities and doesn’t guarantee file recovery. Instead, consider the following alternative recovery methods:

1. Restore from Backups

The most reliable recovery method is to restore files from a pre-infection backup:

• External Backups: Restore from external hard drives, USB drives, or network-attached storage that was disconnected during the infection
• Cloud Backups: Recover files from cloud storage services like Microsoft OneDrive, Google Drive, or Dropbox
• Email Attachments: Check sent emails for previously attached important documents

2. Check for Shadow Volume Copies

While DarkMystic attempts to delete Shadow Copies, this process may not always be complete:

1. Right-click on the folder containing encrypted files
2. Select “Properties”
3. Go to the “Previous Versions” tab
4. If available, select a version from before the infection and click “Restore”

3. Use Data Recovery Software

Some files may be recoverable using specialized software:

• Try data recovery tools that can search for file signatures and recover deleted or overwritten files
• Note that success rates vary significantly depending on the file system, storage type, and time elapsed since encryption

4. Check for Decryptors

While no free decryptor is currently available for DarkMystic, it’s worth monitoring the following resources for updates:

• No More Ransom Project: A collaboration between law enforcement and security companies that provides free decryption tools when available
• Microsoft Security Intelligence: Updates on ransomware threats and potential mitigation strategies

Prevention Strategies: Protecting Against Ransomware

Preventing ransomware infections like DarkMystic requires a multi-layered security approach that combines technical controls with user awareness. Implementing the following preventive measures will significantly reduce the risk of successful ransomware attacks:

1. Implement Robust Backup Strategies

• Follow the 3-2-1 Rule: Maintain at least 3 copies of important data, on 2 different storage types, with 1 copy stored offsite
• Regular Schedule: Perform backups on a consistent schedule (daily, weekly, or monthly depending on data criticality)
• Verify Backups: Regularly test backups to ensure they can be successfully restored
• Offline Storage: Keep some backups disconnected from the network to protect them from ransomware that targets backup systems

2. Keep Systems Updated

• Operating System Patches: Apply security updates for Windows and other operating systems promptly
• Software Updates: Keep all applications, especially browsers, email clients, and document viewers updated
• Enable Automatic Updates: Configure systems to automatically download and install critical security patches

3. Deploy Comprehensive Security Solutions

• Anti-Malware Protection: Install and maintain reputable security software with real-time protection capabilities
• Email Filtering: Implement robust email security solutions that scan attachments and links for malicious content
• Network Security: Utilize firewalls, intrusion prevention systems, and network monitoring tools
• Endpoint Protection: Deploy endpoint protection platforms with behavioral analysis capabilities

4. Enhance User Awareness and Training

• Phishing Awareness: Train users to recognize and report suspicious emails and messages
• Safe Browsing Habits: Educate about visiting only reputable websites and avoiding suspicious downloads
• Attachment Caution: Teach users to be skeptical of unexpected email attachments, even from seemingly known sources
• Regular Simulations: Conduct phishing simulations to test and reinforce security awareness

5. Implement Strong Access Controls

• Principle of Least Privilege: Grant users only the access rights necessary for their job functions
• Multi-Factor Authentication: Require MFA for all accounts, especially those with administrative privileges
• Account Monitoring: Monitor for unusual account activity that might indicate compromise
• Regular Password Changes: Enforce periodic password changes and complexity requirements

6. Implement Network Segmentation

• Separate Critical Systems: Isolate critical systems and data from the general network
• VLAN Configuration: Use VLANs to create logical separations between network segments
• Access Control Lists: Implement strict rules controlling traffic between network segments

Conclusion

DarkMystic (BlackBit) ransomware represents a significant threat to individuals and organizations, employing sophisticated encryption techniques to render files inaccessible and extort victims. Its unique characteristics, including the “.darkmystic” extension and prepended email identifiers, make it easily identifiable but challenging to recover from without proper preparation.

The most effective defense against ransomware attacks like DarkMystic remains a proactive, multi-layered security approach focused on prevention, detection, and recovery capabilities. Regular, tested backups stored offline or in secure cloud environments provide the most reliable recovery method, while comprehensive security solutions and user awareness training significantly reduce the risk of initial infection.

While DarkMystic ransomware can be removed from infected systems using security tools like Trojan Killer, file recovery without backups remains extremely difficult due to the strong encryption employed. Prevention should be the primary focus, with particular attention to email security, system updates, and regular offline backups. Rather than paying ransoms, which funds criminal activities without guaranteeing recovery, organizations should invest in comprehensive security measures and incident response plans to minimize the impact of potential attacks.

For additional information about protecting against ransomware and other malware threats, our comprehensive guides on malware removal, consequences of unremoved malware, and system restoration options provide valuable supplementary resources.