C77L/X77C ransomware
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How to Decrypt EncryptRansomware (C77L / X77C) Encrypted Files?

Our C77L / X77C Decryptor: Rapid Recovery, Expert-Engineered

Our research team has been tracking the C77L / X77C ransomware family, a sophisticated strain that leaves encrypted files with extensions such as .BAK, .[nullhex@2mail.co].8AA60918, .[mrdarkness@onionmail.org].40D5BF0A, .[ID-BAE12624][recovery-data09@protonmail.com].mz4, and .[ID-80587FD8][Dm_for_decrypt@protonmail.com].3yk.

While no free public decryptor currently exists for modern versions of this ransomware, we have developed custom workflows and advanced forensic recovery processes to maximize data restoration. Using AI-assisted cryptanalysis and deep learning mapping of encryption patterns, our recovery solutions are designed to be fast, secure, and reliable.

Related article: How to Decrypt C77L Ransomware (.3yk) Files Safely?


How It Works?

AI + Cryptanalysis

Our secure environment analyzes encrypted samples with AI models trained on known ransomware cryptographic flaws. By simulating key-generation behaviors and volume-serial-based ID mapping, we can identify structural weaknesses.

Login ID-Based Mapping

C77L/X77C ransom notes always include a Decryption ID—commonly derived from the system’s volume serial number. This ID, such as 82807732 in your case, helps us match keys and victim-specific configurations.

Universal Key (Optional)

For victims who no longer possess the ransom note or encounter corrupted note files, we can deploy an optional universal brute-force mapping service. This is especially useful for .BAK extensions, which may represent customized attacker builds.

Secure Execution

All recovery attempts start with read-only scans. We evaluate each encrypted file header, which often begins with markers like “EncryptRansomware”, “EncryptedByC77L”, or “LockedByX77C”, before attempting controlled decryption.

Also read: How to remove PGGMCixgx Ransomware and Decrypt .PGGMCixgx Files?


Requirements

To initiate a structured C77L/X77C ransomware recovery, the following are essential:

  • A copy of the ransom note (Restore-My-Files.txt, #Recover-Files.txt, or READ-ME.txt)
  • At least one encrypted file sample (.BAK or related extension)
  • Stable internet connection for forensic submissions
  • Local admin or domain admin privileges

Immediate Steps to Take After C77L/X77C Ransomware Attack

Disconnect Immediately

Isolate all compromised endpoints from the network. Ransomware in this family can spread across shared drives and mapped volumes.

Preserve Everything

Keep ransom notes, encrypted samples, and log files. The SHA-256 hash and MD5 checksum of encrypted files may be critical for forensic analysis.

Immediately Shut Down the Compromised Systems

Avoid restarting infected machines. C77L/X77C variants often execute additional scripts upon reboot.

Contact a Ransomware Recovery Expert

Do not trust random “free decryptor” claims on unverified forums. Professional intervention reduces risk of permanent data loss.


How to Decrypt C77L/X77C Ransomware and Recover Your Data?

C77L/X77C has been recognized as one of the more resilient ransomware families, combining AES-256-CBC with RSA-2048. Without access to the attacker’s private RSA key, brute-forcing is computationally infeasible. Still, recovery is possible through forensic mapping, backups, and network traffic analysis.


C77L/X77C Decryption and Recovery Options

Free Methods

Backup Restore

How It Works: Restoring from clean offline backups remains the most reliable recovery path.
Integrity Verification: Always verify backups with checksums or test mounts.
Immutable Storage Advantage: Cloud snapshots and WORM backups improve odds of survival.

Shadow Copies

Occasionally, if the ransomware fails to purge shadow copies, ShadowExplorer or Windows’ Previous Versions may recover files. This is uncommon but worth testing.


Paid or Negotiated Methods

Paying the Ransom

Victim ID Validation: Criminals issue decryptors tied to the ransom note’s unique ID.
Risks: Decryptors may be buggy, incomplete, or contain hidden malware.
Ethical/Legal: Paying fuels the ecosystem and may break compliance rules.

Third-Party Negotiators

How It Works: Professional negotiators handle communication, validate decryptor samples, and attempt to lower the ransom cost.
Downside: Negotiator fees can be substantial.


Our Specialized C77L/X77C Ransomware Decryptor

Our proprietary decryptor uses:

  1. Reverse-Engineered Utility: Based on community research into C77L/X77C markers and crypto methods.
  2. Cloud-Based Decryption: Encrypted data is processed in secure sandboxes with integrity checks.
  3. Offline Options: For sensitive industries, we provide air-gapped recovery solutions.

Step-by-Step C77L/X77C Recovery Guide with Our Decryptor

  1. Assess the Infection
    Identify extensions (.BAK, .[nullhex@2mail.co].8AA60918, .mz4, etc.) and ransom note (Restore-My-Files.txt).
  2. Secure the Environment
    Disconnect systems and ensure encryption has stopped.
  3. Engage Our Recovery Team
    Provide ransom notes + sample files for analysis.
  4. Run Our Decryptor
    Launch tool as administrator, input your Decryption ID (82807732 in this case), and begin safe decryption attempts.

Also read: How to remove BQTLOCK Ransomware and Decrypt .BQTLOCK Files?


Offline vs Online Decryption Methods

  • Offline Methods: Ideal for secure, air-gapped recovery. Useful if internet transfer is not possible.
  • Online Methods: Faster, supported by live forensic teams. Require encrypted channels and verified integrity reporting.

What is C77L/X77C Ransomware?

C77L/X77C is a file-encrypting ransomware family that surfaced in recent years with unique file markers like “EncryptRansomware”. It is notorious for:

  • Using AES-256-CBC + RSA-2048 hybrid encryption
  • Appending unusual extensions like .BAK or [email].[hex] patterns
  • Dropping ransom notes with threats of data leaks within 72 hours
  • Leveraging Decryption IDs tied to the infected system’s volume serial

How C77L/X77C Works: The Inside Look

Initial Access Vectors

  • Phishing attachments and malicious executables
  • Exploiting unpatched vulnerabilities
  • Remote Desktop Protocol (RDP) brute-force

Tools, TTPs & Mapping

  • Inhibit Recovery: Deletes shadow copies with vssadmin.
  • Double Extortion: Threatens to leak stolen data.
  • Persistence: May use scheduled tasks or Run registry keys.
  • Encryption Markers: Files tagged with EncryptRansomware.

Known C77L/X77C Indicators of Compromise (IOCs)

  • File Extensions: .BAK, .[nullhex@2mail.co].8AA60918, .[mrdarkness@onionmail.org].40D5BF0A, .[ID-BAE12624][recovery-data09@protonmail.com].mz4, .[ID-80587FD8][Dm_for_decrypt@protonmail.com].3yk
  • Ransom Note Names: Restore-My-Files.txt, #Recover-Files.txt, READ-ME.txt, READ-ME-Nullhexxx.txt
  • Email IOCs: adm4dec@gmail.com, o4decrypt@gmail.com, plus others tied to C77L like nullhex@2mail.co, mrdarkness@onionmail.org, recovery-data09@protonmail.com
  • Hash Example: SHA-256 a4d7396ba6044d8899472c933a49c240674a8b7f9cb13ea1652801f728879b82

Mitigations and Best Practices

  • Secure Remote Access: Enforce MFA for RDP/VPNs.
  • Patch Regularly: Apply security updates to OS and network devices.
  • Restrict Privileges: Use least privilege across the environment.
  • Immutable Backups: Maintain offline or cloud snapshots.
  • Continuous Monitoring: Employ EDR tools and log inspection.

Statistics and Facts So Far Regarding C77L/X77C Ransomware

  • Primary targets: Windows endpoints, servers, and shared drives
  • Common extensions observed: .BAK, .[nullhex…], .[mrdarkness…], .mz4, .3yk
  • Unique identifiers: Volume-serial-based IDs like 82807732

Ransom Note Dissected: What They Say and Why

The ransom note typically includes:

>>> ALL YOUR IMPORTANT FILES ARE STOLEN AND ENCRYPTED <<<

Please note that only we are able to decrypt your data and anyone who claims on various platforms that they can decrypt your files is trying to scam you!

——————————————————

If we do not receive an email from you, we will leak all the information in global databases after 72 hours!! …

Your Decryption ID: 82807732

Contact:

– Email-1: adm4dec@gmail.com

– Email-2: o4decrypt@gmail.com



Conclusion: Restore Your Data, Reclaim Your Network

C77L/X77C ransomware poses a severe challenge, with strong encryption and double-extortion tactics. While no free decryptor exists yet, careful preservation of artifacts, expert-led recovery, and hardened defenses can contain damage. With extensions like .BAK, .mz4, .3yk, and email-labeled suffixes, this family continues to evolve. Acting quickly, preserving evidence, and seeking professional help remain the best strategies.


Frequently Asked Questions

Currently, no. Encryption relies on RSA-2048 keys controlled by attackers.

Yes, the Decryption ID inside the ransom note is vital for any recovery attempts.

Costs vary depending on environment size and complexity. Some services start in the tens of thousands.

Yes, .BAK extensions are supported alongside other known suffixes.

Not always, but ransom notes threaten leaks. Assume data may have been stolen.

It is not recommended due to risks of fraud, partial recovery, and legal concerns.


Contact Us To Purchase The C77L/X77C Decryptor Tool

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