Earlier this year, YouTube added hacking and phishing tutorials to its examples of banned video content — and that ban has been publicized thanks to an apparent crackdown on an ethical “white hat” hacking and computer security channel.

Kody Kinzie is a co-founder of Hacker Interchange, which describes itself as an organization dedicated to teaching beginners about computer science and security. Hacker Interchange produces the Cyber Weapons Lab series on YouTube, but yesterday, Kinzie reported that they were unable to upload new videos because of a content strike. “Our existing content is being flagged and pulled, just got a strike too,” noted Kinzie.

We made a video about launching fireworks over Wi-Fi for the 4th of July only to find out @YouTube gave us a strike because we teach about hacking, so we can't upload it.

YouTube now bans: "Instructional hacking and phishing: Showing users how to bypass secure computer systems"

— Kody (@KodyKinzie) July 2, 2019

The rule is laid out on YouTubes “harmful or dangerous content” page, which bans “instructional hacking and phishing,” i.e. “showing users how to bypass secure computer systems or steal user credentials and personal data.”

As Kinzie and others on Twitter pointed out, even if that could stop some illegal behavior, its potentially terrible news for anybody studying computer security — as well as people interested in countering hacking and phishing tricks. Hacking techniques are often used illegally, but theyre not necessarily illegal. Theyre practiced by many legitimate researchers and computer system testers. YouTube has a similar ban for teaching theft techniques, but thats a much less popular (and expansive) pastime than learning about computers.

However, its not clear exactly how long (or how firmly) YouTube has been enforcing this rule. The Internet Archive shows that its been on the books since at least April 5th, and a YouTube spokesperson tells The Verge that it doesnt represent a new policy — only an example added in a spring update to make the existing rules clearer. YouTube has apparently been taking down hacking videos since well before that date.

YouTubes rules allow depicting dangerous acts “if the primary purpose is educational, documentary, scientific, or artistic (ESDA).” That seems to put an education-focused group like Hacker Interchange in the clear — and many Cyber Weapons Lab videos appear presented in an academic style with a focus on testing security, not committing crimes. But its al