There was even a contest for hiding/obfuscating malicious code, e.g. as an honest mistake: https://www.underhanded-c.org/ . And what do you know, the most recent, common approach shown on the page, is: improper comparison inputs that give unexpected comparison results, which is... well... this submission.
If I had a free afternoon, I'd ask a bunch of agents to track the people responsible and their other contributions (but usually the scheme is "contribute valuable patches to build reputation, and only inject an exploit when safe to do so").