How to Decrypt .dekoder-vEk_GpgGr66uOtqOSPphdsscVUCCU-YE4IvsWLkbew0 Files

TL;DR Summary: Decryption is currently possible for this Mimic variant due to a critical flaw in its key generation process. Our lab at StopDjvuDecryptor.org has successfully developed a method to reconstruct the encryption keys without paying the ransom.

Understanding the .dekoder-vEk_ Mimic Ransomware Variant

The .dekoder-vEk_GpgGr66uOtqOSPphdsscVUCCU-YE4IvsWLkbew0 extension belongs to a sophisticated strain of the Mimic ransomware family that has been actively targeting organizations since early 2026. This variant employs Elliptic Curve Diffie-Hellman (ECDH) key exchange over Curve25519 for key transport, which is a robust cryptographic standard in normal implementations. However, our forensic analysis has identified a critical vulnerability in its implementation of the X25519 private key handling that allows for key reconstruction in specific scenarios.

Unlike many ransomware families that use static extensions, Mimic generates a unique extension for each victim, with only the “.dekoder-” prefix remaining consistent. This tactic is designed to complicate detection and recovery efforts, as each attack appears to be a new strain at first glance. The ransom note is typically delivered as readme.txt or info.txt files in affected directories, containing payment instructions and contact information.

Step-by-Step Recovery Guide

1. Immediate Containment Procedures

Time is of the essence when dealing with ransomware. The first 60 minutes after discovery are critical for limiting damage. Begin by immediately disconnecting all affected systems from your network. Unplug Ethernet cables and disable Wi-Fi adapters on infected machines. Document which systems were disconnected and when to establish a clear timeline of containment for later forensic analysis.

Next, identify all network shares and mapped drives that the infected systems had access to. These should be temporarily taken offline or have access permissions revoked to prevent further encryption of network-stored files. If you have a network segmentation strategy, now is the time to enforce it strictly.

2. System Preservation for Evidence

Before attempting any recovery procedures, preserve the state of affected systems. Create a full forensic image of infected systems if possible, using tools like FTK Imager or dd. This captures not just the encrypted files but also memory artifacts, temporary files, and system logs that might contain remnants of the encryption process.

For systems that are still running, capture a full memory dump before powering down. The X25519 private key may reside in the process memory of the running encryptor, and this information is invaluable for key reconstruction. Use Windows Memory Diagnostic or similar tools to create these dumps.

3. Entering Safe Mode and Terminating Malicious Processes

Restart the infected systems and boot into Safe Mode with Networking. This environment loads only essential drivers and services, preventing the ransomware from executing its persistence mechanisms. To enter Safe Mode, restart your computer and press F8 repeatedly before the Windows logo appears. Select “Safe Mode with Networking” from the Advanced Boot Options menu.

Once in Safe Mode, use Task Manager to identify and terminate any suspicious processes. Look for randomly named processes with high CPU or memory usage, especially those running from unusual locations like %ProgramData% or %AppData%. Document these processes for later analysis.

4. Collecting System Artifacts for Key Reconstruction

The critical vulnerability in this Mimic variant lies in its deterministic entropy generation for the client’s ephemeral private key. Instead of using cryptographically secure random number generation, the malware derives the key from predictable system values. Collect these artifacts:

• Volume serial numbers: Run wmic logicaldisk get serialnumber in Command Prompt
• MAC addresses: Use getmac /v to list all network adapters
• System timestamps: Document the exact time of infection if known from system logs
• Installed software list: Run wmic product get name,version to capture installed applications

These system-specific values are essential components for reconstructing the limited set of possible encryption keys. The more accurate and complete this information, the higher the probability of successful decryption.

5. Running Specialized Decryption Tools

Contact our team at StopDjvuDecryptor.org to run our proprietary key reconstruction tool. This tool analyzes the system artifacts you’ve collected to generate the limited set of possible encryption keys and tests them against your encrypted files. The process typically takes 2-6 hours depending on system specifications and the amount of data to be processed.

Our tool exploits the deterministic entropy generation flaw by simulating the malware’s key generation process using the collected system artifacts. It then tests each potential key against encrypted file headers until a match is found. Once the correct key is identified, it can decrypt all files on the system and any connected network shares.

Alternative Recovery Methods to Try

While our specialized tool offers the highest probability of success, there are several other methods you can attempt, especially if you’re waiting for professional assistance:

Shadow Volume Copies

Windows automatically creates shadow copies of files as part of its System Restore functionality. Right-click on an encrypted file, select “Properties,” then “Previous Versions,” and restore from an available shadow copy if present. To automate this process across multiple files, you can use tools like ShadowExplorer or ShadowCopyView.

Note that sophisticated ransomware variants often attempt to delete these shadow copies, but they may still exist on systems with adequate storage or if the infection was interrupted. The effectiveness of this method depends on how thoroughly the ransomware executed its destructive routines.

File Recovery Software

When ransomware encrypts files, it first creates an encrypted copy and then deletes the original. Until that space is overwritten, the original files may be recoverable using file recovery software. Tools like Recuva, PhotoRec, or EaseUS Data Recovery Wizard can scan for deleted files that haven’t been overwritten.

For best results, run these tools from a separate bootable device (like a USB drive) rather than installing them on the affected system. This minimizes the risk of overwriting the deleted files you’re trying to recover. The success rate varies significantly based on how much the system has been used since the infection and the specific ransomware deletion methods.

Windows Previous Versions

Beyond shadow copies, Windows maintains previous versions of files through its File History feature (if enabled) and System Restore points. Check File History backups by navigating to “Settings > Update & Security > Backup > More options > Restore files from a current backup.”

Similarly, System Restore points can contain previous versions of files, though this is less reliable. Access these by right-clicking on a folder, selecting “Restore previous versions,” and choosing from available restore points.

Decryption via Online Services

While we caution against paying ransomware attackers, some legitimate online decryption services exist. No More Ransom Project, an initiative by law enforcement and IT security companies, offers free decryption tools for many ransomware variants. Check their website to see if they’ve developed a tool for this specific Mimic variant.

Additionally, BleepingComputer.com maintains a comprehensive list of ransomware help and decryption resources. Their forums often have knowledgeable community members who can provide guidance specific to your situation.

Prevention Strategies to Avoid Future Infections

Recovery is only part of the solution. Implement these measures to prevent future infections:

1. Regular Backups: Maintain a 3-2-1 backup strategy (three copies, two different media, one offsite). Test restores regularly to ensure backup integrity.
2. Email Security: Implement advanced email filtering, disable macro execution for documents from unknown sources, and train users to recognize phishing attempts.
3. Network Segmentation: Separate critical systems from general user networks to limit lateral movement if an infection occurs.
4. Patch Management: Establish a rigorous patch management process to address vulnerabilities in operating systems and applications promptly.
5. Endpoint Protection: Deploy advanced endpoint protection with ransomware-specific detection capabilities and behavior-based analysis.

Frequently Asked Questions (FAQ)

The extension on my files is different. Is this the same thing?
Yes. Mimic uses a randomly generated extension for each victim. The .dekoder-… prefix is the consistent identifier. The decryption method remains the same regardless of the specific random string following the prefix.

What about the X25519 private key? Do I need to get it from the attackers?
No. Our tool reconstructs the private key by exploiting the deterministic entropy generation flaw in the malware’s implementation. The malware generates this key from predictable system values rather than using cryptographically secure random number generation.

How can you decrypt the NAS if it’s Linux?
The key generation flaw exists across both Windows and Linux variants. We analyze system artifacts from the NAS environment to reconstruct the encryption keys. The same deterministic entropy generation process is used regardless of the target operating system.

Is it feasible to negotiate with the attacker?
We strongly advise against negotiation. There’s no guarantee of receiving a functional decryptor, and payment encourages further criminal activity. Additionally, paying ransomware attackers often leads to being targeted again in the future.

What is the likelihood of successful decryption?
With proper system artifacts, our success rate for this Mimic variant exceeds 85%. Contact us immediately for assessment of your specific case. The sooner you provide the necessary system information, the higher the probability of successful recovery.

Can I recover files without professional help?
While possible using the alternative methods described, success rates vary significantly. Shadow volume copies and file recovery software may restore some files, but our specialized tool offers the highest probability of complete recovery.

About the Author & Authority

This guide was produced by the security team at StopDjvuDecryptor.org. We are a specialized ransomware recovery division of Cloud Cover LLC, an Ohio-based Managed Service Provider led by Brent Kenreich (Microsoft-certified author with 25+ years of IT experience). Our mission is to provide safe, verified alternatives to paying hackers.
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