I'm planing a question/puzzle, with pitch on the tune of
The International Stamped Time Server (ISTS) broadcasts, every minute, a time stamp integrity-protected with RSA-4096. Days after it starts operation, hackers announce they pwned it by rigging the RSA cryptoengine, and publish a valid stamp for year 9999 as a proof. That stamp couldn't have been made by the ISTS. You wrote the key generator and supervised key insertion in the cryptoengine, and must clear yourself from suspicion by finding how the hackers have proceeded.
The rest describes the ISTS, its simple signature format, its implementation, and precautions taken, including to catch malfunction of the cryptoengine or exfiltration of its content. The statement has no ciphertext or large numbers. The solution involves RSA and information theory, not IT security. There are two levels of answering: finding the general principle used, which I expect will be easy; finding how the hackers managed it that fast, and the fastest they could have made it.
Would that be on-topic?