Our GandCrab Decryptor — Professionally Developed for Legacy Infections
Our incident response team has developed a specialized decryptor for GandCrab ransomware (v1), a legacy threat family first observed in early 2018. GandCrab is one of the earliest large-scale ransomware-as-a-service (RaaS) operations, known for its widespread use of affiliates and its evolution through versions V1 to V5.2.
The GandCrab V1 variant encrypts user data with a combination of RSA-2048 and AES-256 algorithms and appends the “.GDCB” extension to files, leaving ransom notes named GDCB-DECRYPT.txt.
Our decryptor has been carefully reverse-engineered and tested to:
Analyze encrypted samples in a secure sandbox environment;
Detect version-specific encryption patterns and victim identifiers; and
Perform verified decryption while generating audit and validation logs for data integrity.
The decryptor can function in cloud-assisted or offline recovery environments. Each session begins with read-only verification, ensuring that encrypted evidence remains preserved and tamper-free.
When victims provide encrypted samples and ransom notes, our decryptor identifies the variant version by examining cryptographic signatures and RSA key pair markers. It cross-references these against known GandCrab key structures used between 2018–2019. If the encryption headers match, a Proof-of-Concept (PoC) decryption is performed on a small sample file. Once confirmed, full restoration is executed while logging all recovery actions for compliance and evidence tracking.
Requirements:
A ransom note named GDCB-DECRYPT.txt
Two to five encrypted file copies ending with .GDCB
Administrator privileges on a recovery workstation
Optional internet access (for cloud decryption verification)
Disconnect infected devices from networks, Wi-Fi, and cloud storage to prevent the ransomware from spreading further.
Preserve all encrypted files and ransom notes in their current state. Do not attempt renaming, modification, or manual decryption.
Perform a memory dump (if possible) to extract residual keys or runtime artifacts.
Gather all relevant logs and telemetry, including antivirus alerts, firewall events, and Windows event logs.
Engage a verified ransomware recovery team rather than attempting to use unverified decryption tools found online.
Recovery Options for .GDCB Files
Free Recovery Solutions
Use of Official Bitdefender Decryptor Bitdefender, in collaboration with law enforcement, released an official GandCrab decryptor for versions V1, V4, and V5–V5.2. Victims running these variants can use the free tool to restore their files, provided the tool can connect to the internet for key verification.
Offline Backups If backups were maintained before infection, restore files from those copies after confirming their integrity. Disconnect backups before recovery to prevent accidental encryption of clean data.
Paid or Professional Recovery Services
Analyst-Led Decryption Our recovery service is designed for cases where Bitdefender’s decryptor fails or does not detect the variant properly. Our analysts conduct a PoC test on sample files before proceeding with full recovery.
Ransom Payment (Not Advised) Although GandCrab’s original servers are offline, some legacy operations or rebrands may attempt re-extortion. Paying ransoms is highly discouraged, as the decryption keys for older variants were destroyed when the GandCrab operation officially shut down in mid-2019.
How to Use Our GandCrab Decryptor — Step-by-Step?
Assess the Infection Check if encrypted files end in .GDCB and confirm that the ransom note GDCB-DECRYPT.txt exists in affected directories.
Secure the System Disconnect all compromised systems and ensure no encryption processes are still running in memory.
Engage Our Recovery Team Submit encrypted samples and ransom notes to our secure portal. Our team will identify the version and prepare a recovery strategy.
Run the Decryptor Launch the GandCrab Decryptor as an administrator. An internet connection may be required for cloud key validation.
Enter Victim ID (if prompted) The ransom note or encryption metadata may contain an identifier unique to your case. Enter it in the decryptor to match the correct session keys.
Start Decryption Begin the restoration process and allow the decryptor to recover files in a separate directory. Integrity reports will be provided upon completion.
Overview GandCrab ransomware, first reported in January 2018, was one of the first ransomware-as-a-service (RaaS) models to dominate the threat landscape. Affiliates rented access to the malware for a share of ransom profits. Version 1, known as GDCB, used RSA-2048 and AES-256 hybrid encryption and was distributed through spam emails and exploit kits.
Evolution & Legacy Over its lifecycle, GandCrab evolved into multiple versions — each improving encryption strength and evasion tactics. It was officially “retired” in 2019 after the operators claimed to have earned over $2 billion USD in ransom profits. However, GandCrab’s source code inspired newer ransomware families such as REvil (Sodinokibi), which emerged shortly after.
Impact GandCrab primarily targeted Windows systems, encrypting files and replacing desktop wallpapers with ransom messages. While the operation has ceased, encrypted data from historical attacks remains locked if victims never recovered their decryption keys.
Ransom Note — GDCB-DECRYPT.txt
File Name: GDCB-DECRYPT.txt Distribution: Dropped into each folder containing encrypted files.
Excerpt from GandCrab Ransom Note:
Your files have been encrypted! All your documents, photos, databases, and other important files are no longer accessible. To restore your files, you must purchase a decryption tool. Do not attempt to modify or rename encrypted files — this may result in permanent data loss. Visit the following URLs through a TOR browser for payment instructions.
Attention: Decrypting files using third-party tools may cause corruption. If you value your data, follow instructions carefully.
Encrypted files inaccessible without original keys
Tactics, Techniques & Procedures (TTPs)
Initial Access: Spam campaigns, exploit kits, and malicious attachments
Execution: Encryption via AES/RSA hybrid system
Persistence: Registry modifications and auto-run entries
Defense Evasion: Obfuscation and shadow copy deletion
Impact: File encryption, ransom note generation, and data loss
Victim Landscape
Regions Affected:
Industries Impacted:
Timeline:
Conclusion
GandCrab ransomware remains a landmark in the evolution of modern cyber extortion. Its widespread use of affiliate networks, hybrid encryption techniques, and fast version updates reshaped how ransomware operations function today. Although the gang behind GandCrab disbanded years ago, its legacy lives on through its descendants, such as REvil. For those still affected by early variants like .GDCB, recovery is possible only through verified decryptors like Bitdefender’s official tool or professional services that specialize in legacy ransomware recovery. Organizations should continue to maintain offline backups, enforce robust email security, and update endpoint defenses to prevent similar ransomware infections from emerging in the future.
Frequently Asked Questions
Yes, Bitdefender released a free decryptor for versions V1, V4, and V5–V5.2.
RSA-2048 and AES-256 hybrid encryption.
Via spam emails, exploit kits, and malicious file attachments.
No. The operators shut down in 2019 and deleted all keys.
Maintain multiple offline backups, update antivirus software, disable macros, and exercise caution with email attachments.
Contact Us To Purchase The GandCrab Decryptor Tool
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