This wasn't just capable last year, it was capable prior to ChatGPT existing entirely through specialized automation harnesses that predate the terminology of a "harness" for models. This is something you could have done in 2018 if you had a spare couple of billion dollars of compute to waste. It was a subject discussed at security conferences even before that.

Automated dynamic exploit chains and credential discovery has been something every red team worth their salt does at a lesser scale for 20 years, why would you ever think that the capability didn't exist until it only cost a few thousand dollars to do?

Existed does not mean was easy, or was cheap, or was thought of as reasonable to attempt.

Also, IQ is not a term that applies to language models, and the term you are looking for is "Long Horizon Coherence".