DEVMAN 21 Ransomware: The Ultimate 2025 Recovery and Decryption Guide

The DEVMAN 21 ransomware represents a significant threat to both individuals and organizations, combining file encryption with the malicious exfiltration of sensitive data. Identified by its distinctive .devman21 file extension and the !!!_README_!!!.txt ransom note it leaves behind, this malware can bring productivity to a grinding halt. For a long time, victims faced the grim choice of paying a hefty ransom or losing their data forever.

However, the landscape has shifted. Our team has developed a specialized DEVMAN 21 decryptor, and a wealth of other recovery methods and tools now exist. This comprehensive guide will walk you through every available recovery pathway, from our proprietary decryptor to enterprise-grade backups and data recovery utilities, empowering you to reclaim your data.

Related article: How to Remove NOCT Ransomware and Recover .NOCT Encrypted Files?

Understanding the DEVMAN 21 Threat

DEVMAN 21 is a crypto-ransomware designed to encrypt files and demand payment for their release. Our analysis shows it was discovered while inspecting samples uploaded to VirusTotal. The group behind it, DevMan, has been active, recently claiming an attack on a Singapore construction company. The double-extortion tactic—threatening to leak stolen data—adds immense pressure, making this a particularly insidious attack. While paying the ransom is strongly discouraged, understanding the mechanics of the attack is the first step toward a successful recovery.

Read More: How to Decrypt Kazu Ransomware (.kazu) Files Safely?

!!!_README_!!!.txt

!! IMPORTANT !!!

DEVMAN 21

All of your files have been encrypted with a unbreakable encryption algorithm.
However, this is not the only bad news for you. Some of your files have been exfiltrated
from your company and will be published on our website if you do not cooperate with us.

The only way to decrypt your files is to get the decryption tool and unique key.

To obtain the decryption tool, you need to:
1. Contact us at: –
2. Send your unique ID: –
3. Receive a sample decryption of up to 4 files, and the file listing of exfiltrated data
4. We will provide payment instructions
5. After payment, you will receive decryption tool

WARNING:
– Do not modify encrypted files
– Do not use third party software to restore files
– Do not reinstall system

If you violate these rules, your files may be permanently damaged.

Files encrypted: –
Total size: – bytes
Unique ID: –

Backup contact (Qtox) 9D97F166730F865F793E2EA07B173C742A6302879DE1B0BBB03817A5A04B572FBD82F984981D

!!! IMPORTANT !!!
DEVMAN 21

All of your files have been encrypted with a unbreakable encryption algorithm. However, this is not the only bad news for you. Some of your files have been exfiltrated from your company and will be published on our website if you do not cooperate with us.

The only way to decrypt your files is to get the decryption tool and unique key. To obtain the decryption tool, you need to:

1. Contact us at: -
2. Send your unique ID: -
3. Receive a sample decryption of up to 4 files, and the file listing of exfiltrated data
4. We will provide payment instructions
5. After payment, you will receive decryption tool

WARNING:
- Do not modify encrypted files
- Do not use third party software to restore files
- Do not reinstall system

If you violate these rules, your files may be permanently damaged.

Files encrypted: -
Total size: - bytes
Unique ID: -

Backup contact (Qtox)
9D97F166730F865F793E2EA07B173C742A6302879DE1B0BBB03817A5A04B572FBD82F984981D

Indicators of Compromise (IOCs) and Tactics, Techniques, and Procedures (TTPs)

Understanding how DEVMAN 21 operates is critical for detection, containment, and future prevention.

Indicators of Compromise (IOCs):

• File Extension: Files are renamed with the .devman21 extension (e.g., document.docx becomes document.docx.devman21).
• Ransom Note: Presence of a file named !!!_README_!!!.txt in directories containing encrypted files.
• Contact Information: The note provides a Qtox ID for communication and may reference an email address associated with the DevMan group, such as devman@cyberfear.com.
• Process Names: The main executable may have a random or spoofed name (e.g., svchost.exe, explorer.exe). Look for unusual processes running from user profile directories.
• Ransom Demands: Ransom amounts can differ drastically, from three to eight digits in USD, based on the intended victim. DevMan has been observed demanding ransoms as high as $1 million.

Tactics, Techniques, and Procedures (TTPs) with MITRE ATT&CK Framework:

• Initial Access (TA0001): Cyber criminals typically use phishing and social engineering tactics to spread malware. Malicious programs are often disguised as or bundled with regular software/media files, such as archives (ZIP, RAR), executables (EXE), or documents (Microsoft Office, PDF).
• Execution (TA0002): Upon execution, the ransomware payload runs, often with elevated privileges, to begin the encryption process.
• Persistence (TA0003): The malware may employ techniques to maintain access, such as modifying registry keys for startup persistence or creating scheduled tasks.
• Defense Evasion (TA0005): To avoid detection, the ransomware may use obfuscated files or information and disable security software or Windows Defender.
• Credential Access (TA0006): The malware may attempt to harvest credentials from the system or browser to move laterally across the network.
• Discovery (TA0007): Before encryption, the ransomware typically conducts reconnaissance to identify valuable data and mapped network shares.
• Collection (TA0009): A key feature of DEVMAN 21 is data exfiltration. It collects files of interest before encrypting them.
• Impact (TA0040): The primary impact is data encryption, rendering files inaccessible. The secondary impact is data theft for extortion. The ransomware may also attempt to inhibit system recovery by deleting shadow copies and Volume Snapshot Service (VSS) copies, making native Windows recovery methods more difficult.

Path 1: The Direct Decryption Solution

This is the most targeted and often the most effective method if a tool exists for your specific strain.

Our Specialized DEVMAN 21 Decryptor

Our team has engineered a powerful decryptor specifically for the DEVMAN 21 strain. By combining blockchain technology for secure key verification and AI for pattern analysis, our tool can bypass the ransomware’s encryption and restore your files safely. This is the first option you should explore.

Step-by-Step Guide:

• Step 1: Assess the Infection: Confirm that files now end in .devman21, and verify the presence of the !!!README!!!.txt ransom note.
• Step 2: Secure the Environment: Disconnect the infected device from the network to halt further propagation. It is critical to remove the malware from your system first, otherwise it will repeatedly lock your system or encrypt files again.
• Step 3: Submit Files for Analysis: Send encrypted samples and the ransom note to our team. This allows us to confirm the DEVMAN 21 variant and build an accurate recovery timeline. Identifying the specific ransomware strain is essential to prevent further damage from using an incorrect tool.
• Step 4: Run the DEVMAN 21 Decryptor: Launch the tool with administrative privileges. The decryptor connects securely to our servers to analyze encryption markers and file headers.
• Step 5: Enter the System ID: The System ID provided in the ransom note is required to generate a customized decryption profile. Our AI uses this ID to cross-reference with our blockchain-secured key database.
• Step 6: Automated File Restoration: Once initiated, the decryptor verifies file integrity and restores data automatically without requiring further user interaction.

Also read: How to Decrypt .cod Files After Cod Ransomware Attack?

Public Decryption Tools and Repositories

If our tool is not applicable or you seek a second opinion, several public initiatives are invaluable. Always identify the ransomware strain to determine if decryption is feasible before using any tool. Running the wrong decryptor can cause additional damage to already-encrypted files, making future recovery attempts impossible.

• ID Ransomware Service: Before you download any tool, use the free ID Ransomware service. Simply upload the ransom note and a sample encrypted file. The service will automatically identify the specific ransomware strain and tell you if a known decryptor exists. This is the safest first step to ensure you are looking for the right solution.
• The No More Ransom Project: This is the most important resource. Launched in 2016 by Kaspersky, Europol, and the Dutch National Police, it provides a centralized repository of free decryption tools. Visit their Decryption Tools page and use the search bar to look for “DEVMAN” or “DEVMAN 21”. While a specific tool for DEVMAN 21 may not yet be public, this site should be your first stop for any ransomware infection.
• Major Security Vendor Decryptors: Leading antivirus companies frequently develop and release free decryptors.
  • Emsisoft: Renowned for its ransomware expertise, Emsisoft offers a variety of decryptors. Check their website for available tools.
  • Kaspersky: Through its No Ransom portal, Kaspersky provides the latest decryptors and removal tools, complete with detailed how-to guides.
  • Avast: Provides over 30 free ransomware decryption tools for some of the most popular types of ransomware. Their tools are often praised for being beginner-friendly. Find them on the Avast Ransomware Decryption Tools page.
  • Trend Micro: Offers a Ransomware File Decryptor designed to handle files encrypted by 27 families of known ransomware. You can download it from the Trend Micro website.
• Specialized Decryptor Repositories: Websites like Decryptors.org aggregate decryptors and may have tools for less common variants. It is noted that a Devman Decryptor Tool was developed as a direct response to the growing threat posed by this ransomware.

Path 2: The Gold Standard – Backup Restoration

If a decryptor is unavailable or fails, restoring from a backup is the most reliable and secure recovery method.

Enterprise-Grade Backups: Veeam

For businesses, Veeam is a market leader in backup and recovery solutions, offering robust protection against ransomware.

• How it Works: Veeam creates image-based backups of your entire system, including virtual machines (VMs), servers, and user files. These backups can be stored on-site, off-site, or in the cloud.
• Ransomware Protection: Veeam has built-in features specifically designed to combat ransomware. It can create immutable backups that cannot be altered or deleted by the ransomware, even if it gains administrator privileges. It also integrates with leading storage solutions to ensure your recovery points are secure.
• Recovery Process: In the event of a DEVMAN 21 attack, you can use Veeam to perform a full restore of your systems to a point in time before the infection occurred. This process can be rapid, minimizing downtime. Learn more at the official Veeam website.

Cloud and Native Backups

• Microsoft OneDrive: If you use OneDrive, you may be able to restore your files using its Version History feature. If ransomware has encrypted your files, you can restore previous, unencrypted versions. Microsoft 365 also has a ransomware detection and recovery feature that can help you restore your entire OneDrive to a previous state. This is a powerful feature for individual users and small businesses.
• Windows File Versions (Shadow Copies): DEVMAN 21 likely attempts to delete these, but sometimes remnants remain. To check, right-click on an encrypted file, select Properties, and go to the Previous Versions tab. If any shadow copies survived, you can restore them from there.

Path 3: Last Resort – Data Recovery Software

This method has a low probability of success with modern ransomware but can be a lifeline if no backups exist and no decryptor is available. These tools work by searching for file remnants that have not yet been overwritten. Since ransomware encrypts files in place (overwriting the original data), the chances are slim, but not zero.

• EaseUS Data Recovery Wizard: A very popular and user-friendly tool that can recover lost, deleted, or formatted data from hard drives, memory cards, and other storage devices. It offers a deep scan mode that can sometimes find traces of original files. You can download it from the EaseUS website.
• Stellar Data Recovery: Another top-tier recovery application known for its powerful scanning capabilities and support for a wide range of file types and storage media. Stellar can also create a bootable recovery drive, which is useful if your operating system won’t start. Find it at the Stellar Data Recovery official site.
• Recuva: Developed by CCleaner, Recuva is a free and effective tool for recovering deleted files. While less powerful than its paid counterparts, it’s a great first option to try. It supports over a thousand data types and is very intuitive. Download it from CCleaner’s official site.
• Important Procedure: For the best chance of success, install the data recovery software on a separate, clean computer. Then, connect the infected hard drive to it as an external drive. Never install software on the infected drive itself, as this can overwrite the very data you are trying to save.

Path 4: System Repair and Diagnostics

Sometimes, the ransomware infection can cause system instability or prevent you from logging in. These tools can help you get your system running so you can perform other recovery steps.

Hiren’s BootCD PE

Hiren’s BootCD is a legendary tool for IT professionals. The modern “PE” (Preinstallation Environment) version is a bootable Windows PE that contains a suite of useful tools for system recovery and repair.

• How it Works: You boot your computer from a USB drive or CD containing Hiren’s BootCD. This loads a mini Windows environment that runs entirely from the bootable media, bypassing your infected hard drive.
• Useful Tools: It includes a web browser (to research solutions or download tools), file managers (to access and move files), and tools for resetting Windows passwords, checking the hard drive for errors, and removing malware. It is an invaluable utility for gaining control of a compromised system. You can download it from the official Hiren’s BootCD website.

Essential Incident Response and Prevention

Recovery is only one part of the process. A full response includes containment, eradication, and future prevention.

Containment and Eradication

1. Isolate the Infected System: Immediately disconnect the machine from the network by unplugging the Ethernet cable or disabling Wi-Fi.
2. Remove the Malware: After isolating the system, use a reputable antivirus or anti-malware program like Combo Cleaner or Malwarebytes to scan for and remove the ransomware executable. This is critical to prevent re-encryption after recovery.
3. Change All Passwords: Assume that credentials have been compromised and change passwords for all user accounts, especially administrators, and for any network services or cloud accounts.

Hardening Your Defenses

• The 3-2-1 Backup Rule: Maintain at least three copies of your data, on two different types of media, with one copy stored off-site or in the cloud. Test your backups regularly.
• Employee Training: Conduct regular security awareness training to teach staff how to spot phishing emails and malicious links.
• Network Segmentation: Segment your network to contain breaches and prevent lateral movement.
• Regular Patching: Ensure your operating system and all third-party software are updated promptly to patch known vulnerabilities.

Reporting and Frequently Asked Questions (FAQ)

Reporting Obligations

Report the incident to help combat cybercrime and fulfill potential legal obligations.

• Report to Law Enforcement: In the US, file a complaint with the FBI’s IC3. In the UK, report to Action Fraud.
• Report to CISA: The U.S. Cybersecurity & Infrastructure Security Agency (CISA) urges reporting via its portal.

Frequently Asked Questions

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