I meant "smoking gun" from a cyber security perspective, i.e. the conclusion or the final part of the investigation. "magic bullet" would also work here too though.
You seem to have inferred the wrong meaning of "smoking gun" and that's why your usage above doesn't make sense.
There's no valid reason cyber security people would take a well known idiom and repurpose it as you imply, and a quick Google suggests they haven't done this.
Even with your explanation I don't think it fits here.
[1] https://en.m.wiktionary.org/wiki/smoking_gun