As quoted in:

Cox, Joseph. “Hackers Are Targeting Schools in a Wave of Tax Info Phishing Attacks.” Motherboard. 13 February 2017.

“There is a pretty unusual and unprecedented phishing attack targeting schools right now; it may have resulted in the disclosure of tens of thousands of educators’ financial records (W-2s),” Doug Levin, the founder and president of EdTech Strategies, told Motherboard in an email.

…

“My guess is the bad guys figured out how susceptible .edu email addresses are. Phishing can be tough for even sophisticated targets, but K-12 schools are definitely not that,” Levin told Motherboard.