Wasn't the original backdoor in a code example the NSA provided to companies interested in using cryptography? They gave an example seed or whatever, and most c

Wasn't the original backdoor in a code example the NSA provided to companies interested in using cryptography? They gave an example seed or whatever, and most companies copy/pasted it instead of generating their own primes, so the NSA could break it trivially. My memory around this is fuzzy and I can't seem to find the original source.