Comment by solid_fuel

It's structurally impossible. LLMs, at their core, take trusted system input (the prompt) and multiply it against untrusted input from the users and the internet at large. There is no separation between the two, and there cannot be with the way LLMs work. They will always be vulnerable to prompt injection and manipulation.

The _only_ way to create a reasonably secure system that incorporates an LLM is to treat the LLM output as completely untrustworthy in all situations. All interactions must be validated against a security layer and any calls out of the system must be seen as potential data leaks - including web searches, GET requests, emails, anything.

You can still do useful things under that restriction but a lot of LLM tooling doesn't seem to grasp the fundamental security issues at play.