white hat
1 : one who is admirable and honorable
2 : a mark or symbol of goodness
3 : a hacker who tests computer systems for possible vulnerabilities so that they can be fixed

2 : a person who intentionally antagonizes others online by posting inflammatory, irrelevant, or offensive comments or other disruptive content • Internet trolls

“white hat” and “troll.” Merriam-Webster.com. 2018. https://www.merriam-webster.com (28 February 2018).