War With Black Iris by D. B. Goodin

Solving cryptographic puzzles is fun…unless the puzzle is designed to kill
you.

Nigel Watson is a clever teenage hacker who narrowly escaped with his life in
White Hat Black Heart. Unable to speak, he must find a new way to thwart a
mysterious threat that is taking over the world’s computer infrastructure.

Artificial intelligence has become self-aware…and determined people must die.

A rogue billionaire attempts to save the life of his ailing grand-daughter by
transferring her consciousness into a healthy cyborg host. But, malfunctions within the
cyborg’s system transform it into a sentient being capable of destroying humanity.

Two hacking groups, the Collective and Black Iris, join forces with Nigel to fend off
the cyborg’s attacks. But, some of his friends are kidnapped and forced to work
against him.