Hi guys,
I have a mission to unlock some briefcase, but the F / X button are disabled because it says 6/7 hacking.
How to increase it? I tried to google but did not find any information, and the character menu is so overwhelemed with options.
Please help me!

Use the Intelligence :D No pun intended :D

You have to raise intelligence.
After every levelup you will get a attribute point.
Open character menu (where you see your attributes reflexes, intelligence, coolness etc.)
Move your cursor to intelligence but don't click on it.
Hold F and you will raise intelligence by 1 point.