It is pretty simple to prevent a rogue AI from hacking a third party. Make the system air gapped completely. You want a cache of internet or artifacts, you bring those into the air gapped data center, plug in, copy. You want info out, you go in, you collect, and inspect the inert data outside of the dangerous agents farm.
None of this is a surprise. An agent is a user. An unaligned agent should never be in any environment with a path to the internet.
It's not difficult to do any of this, just tediously inconvenient.