Good day fellow chummers!
Recenetly I've been attacked by an enemy decker's Brute Force. Is there any way I can find this not-very-good-guy on the spot? He managed to hit me, so I'm aware about his attack on me. Can I find him in a vicinity with my Matrix Perception roll?
See the Matrix Spotting table, pg. 234 SR5.
If the enemy decker is running silent: it always takes a successful Matrix Perception roll.
If the enemy decker is NOT running silent, and is physically within 100m of you: no Matrix Perception roll is necessary
If the enemy decker is NOT running silent, but is physically more than 100m away from you: it takes a successful Matrix Perception roll. And don't forget to account for the distance-based Noise, as well!
Generally it's a question regarding travelling in the Matrix. Does my Persona really travel to the file I want to interract with?
you don't "move" in the matrix. At best, the comparison of where your persona is in the matrix compared to where you physically are is a non-sequitur.
If you want to mess with a file on a host, you first virtually enter said host, even though your physical location hasn't changed.
If you want to mess with a file on a commlink, you just "directly" mess with it, accounting for any distance-based Noise if applicable.
And the second question is: Does a host see my illegal activity when place a mark with the Brute Force?
The target of a successful Brute Force always notices. However, if you're running silent, it doesn't mean they SEE you. But if you have a mark on them, they can always see your mark (assuming they can get 1 hit on an unopposed Matrix Perception test...) so they've always got "something" to go on to keep searching for you pass after pass, round after round, until you're spotted... if they go long enough without being able to spot you (or be successful on an Erase Mark action on their own icon), they can also decide to "frag it" and either reboot the device to forcibly erase your mark, or just go wireless-off to remove your ability to communicate with the hacked device.