Nexon Korea Security Breach

"Nexon discovered on Thursday that millions of user IDs, players' names, passwords and residential registration numbers on MapleStory was leaked from its servers to unidentified hackers."
Passwords in plaintext? It doesn't specify...

Next sentence.

"Passwords and residential registration numbers, an equivalent of social security numbers in the United States, were encrypted, but affected users were still advised to change their passcodes on other Web sites, the company added."