Ok, so you’ve hacked into a host, now you’re moving around inside, trying to find that file you need. But will the host spot you? Do you need to be doing something illegal to get spotted, or can you just blend in til you find what you’re after? How does the host know you’re a hacker, and not just a legitimate user? Stay tuned…

Ok, so first off, if you’re inside a host, then you need to evade its Patrol IC (p. 248, SR5). Almost all hosts have Patrol IC running, and checking out any visitors. It uses the matrix perception action (p. 241, SR5), which will be its rating x2. For every hit it gets, it can determine one piece of information about that icon (p. 235, SR5).

But if you’ve just made a successful Hack on the Fly to gain a mark, and enter, and you’re just wandering around the host without causing any trouble, why would the host take any notice of you? Well, one of the items of info it can snag about you is the last matrix action performed and when. And if that was Hack on the Fly, or anything else illegal, it’s a dead giveaway…

So how often does Patrol IC get to scan you over? It varies according to the rating of the host (p. 86, DT). Starting at once per turn for rating 1-2, every 2D6 turns at rating 7-8, and everything in between. If an alarm is raised, though, this will likely drop to once per turn. These time intervals are for lazily scanning everything in the host.

Now notice that you can get a lot done in a few combat turns. However, if you’re looking for a file or some such, it can take a minute or so, as you’ll need to make a Matrix Search (p. 241, SR5), but can be a lot faster with lots of successes, and the Browse program halves the time. Very handy.

Ok, so staying hidden for a time is useful, we can agree. What about Running Silent (p. 235, SR5)? Just a simple action, -2 to all matrix actions, then you’re invisible, right?

Well, essentially yes. Although, if the host has a mark on you, you can’t run silent, you are automatically spotted. You’ll need to scrub that mark asap.

What if you’re running silent, and there’s no mark on you? Well, for the time being, you should be safe. However, matrix perception (remember that Patrol IC), can be used to check “Are there any icons running silent around here?” Once its established that there are, it can take a further matrix perception action, to actually detect a silent icon. This takes Computer + Intuition (Rating x2) vs your Logic + Sleaze, to spot you. In a low host, with a good enough sleaze rating, you may stay hidden for the duration of the hack.

Would Patrol IC be routinely looking for silent icons? That’s really a question for the GM. Probably a high level host, protecting very secure data would look with every sweep, but other hosts might not bother.

But if suspicious activity started to be detected, then this posture might change quickly. Again, it’s more a matter of flavour than rules.

Once you are spotted, if you don’t have any marks on you, then you can still try to get away, using the Hide action (p. 240, SR5). This negates the host’s successful spot of your icon, and means you are once again evading, whether running silent or not. Remember: if the host has marks on you, it always knows where you are, running silent or otherwise.

So, if you’re the sneaky type, you could keep running silent and hiding until you’ve got what you came for. But don’t forget about convergence. Sooner or later, you’ll hit that 40 figure, and the host will get 3 marks and IC will come crashing in on you.

I hope this clears up any confusion about how to stay hidden in the host, and what you can and can’t get away with.

Thanks to the Bald Man for helping me out with some rules queries.