This character is a hacker.

A hacker is a person who delights in having an intimate understanding of the internal workings of a system, computers and computer networks in particular.

Modern popular use of the term refers to people committed to circumvention of computer security. This primarily concerns unauthorized remote computer break-ins via a communication networks such as the Internet (Black hats), but also includes those who debug or fix security problems (White hats), and the morally ambiguous Grey hats.