2016 FBI hack
One Justice Department employee’s email account. That’s all it took for a hacker to become privy to every single person who works for the FBI and the Department of Homeland Security. From that compromised account, he was able to download roughly 200 GB of incredibly sensitive info, like a real version of the Mission: Impossible NOC list. He then tricked a DOJ rep into giving him access to the database itself.
The names, rank, and personal information of nearly 30,000 employees who work in a very guarded profession immediately had their cover blown. Phone numbers and email addresses were made public, and the hacker stated he had credit card numbers as well. The hacks were apparently done by someone with pro-Palestine sympathies. That someone, it turns out, was a 16-year-old teenager living in England.