The measures are rather extreme and apparently include surveillance of the individual in question, as well as internal presentations and instructions on how to approach him.
This comes courtesy of prominent Twitter Nintendo leaker Eclipse.
According to documents unearthed by Eclipse - which also include a Switch software development kit and console security documents, among other things - the company conducted surveillance on Neimod, a hacker who cracked the 3DS, in 2013.
Online Nintendo historian Forest of Illusion corroborates this with an internal document showing findings about Neimod's personal life including where he lived and his average work week.
Some of the documents from twitter:
In addition to the surveillance, Nintendo also created detailed plans on how to approach Neimod in order to get him to back down from hacking the 3DS.
In the documents, IRC chats involving Neimod are included, showing Nintendo covertly extracting information from Neimod and altering its response to the issue based on what he says.
The details of Nintendo's plan to approach Neimod are remarkably detailed, with multiple stages and potential outcomes mapped out in a flowchart.
There's also a detailed plan in the Nintendo leak regarding exactly how Nintendo planned to approach Neimod, including timestamps. In these plans, a "contact team" would approach Neimod after he arrived home on a Monday.
The team would approach him in a "friendly, non-threatening, professional, and courteous manner", praising him for his "engineering/programming aptitude" and requesting that he "discontinue hacking of Nintendo systems/products".
If a resolution was not reached, Nintendo intended to "pursue a criminal referral" and show Neimod a draft complaint to "demonstrate severity and seriousness".
Source with more detail about Nintendo's history with hackers:
An internal Nintendo leak has revealed measures the company took when approaching a 3DS homebrew hacker. The measures are rather extreme and apparently include surveillance of the individual in question, as well as internal presentations and instructions on how to approach him.