https://www.theregister.co.uk/2019/12/16/internet_of_crap_encryption/

A preponderance of weak keys is leaving IoT devices at risk of being hacked, and the problem won't be an easy one to solve.

This was the conclusion reached by the team at security house Keyfactor, which analyzed a collection of 75 million RSA certificates gathered from the open internet and determined that number combinations were being repeated at a far greater rate than they should, meaning encrypted connections could possibly be broken by attackers who correctly guess a key.