Nir Gaist is just 25, but he’s been exploring the ins and outs of cyber security for more than half his life. When he was 10, Israel’s largest banks hired him to hack into their systems — to learn how to prevent malicious hackers.Nir Gaist is just 25, but he’s been exploring the ins and outs of cyber security for more than half his life. When he was 10, Israel’s largest banks hired him to hack into their systems — to learn how to prevent malicious hackers.