Ransomware Decryption Without Paying: A Race Against Time

The author successfully helped a company recover its data from Akira ransomware without paying the ransom, and has open-sourced the full source code. The ransomware uses four nanosecond timestamps as seeds to generate encryption keys. By analyzing the ransomware's encryption algorithm and filesystem timestamps, the author devised a GPU-accelerated brute-force solution. This involved enumerating timestamp combinations, generating keys, and attempting to decrypt known plaintext. The process was challenging, requiring reverse engineering, CUDA programming optimization, and cloud computing resources. The author shares technical details and code, providing a valuable resource for data recovery in similar situations.