Respuestas al mensaje #4

Scanned for what, are you going to ban hyperlinks?

Easiest answer: "It's complicated". These come in via any angle you can imagine, guessed passwords (spraying, for instance), phishing, malware...

There's not much they can do besides filtering. I've seen a few software developers fall for phishing links, so I doubt any amount of training...

They could have just found an obvious hole in the school's network or done phishing as you say. A lot of them find targets that are more likely to...

Thats one vector. Could be unpatched vulnerabilities. Could be some sort of social engineering. Could be someone running a malicious macro/script...