Gamers beware: hackers offering free virtual trinkets don't care about your passwords or personal data — they are after your employer's most closely guarded secrets.

An employee at a Japanese high-tech company learned this the hard way, duped by a fake giveaway for 300 magic stones for the smartphone game "Puzzle & Dragons."

"Congratulations," began the email promoting free in-game currency for the first 100 lucky takers: "Click here!" That initiated a drive-by download that surreptitiously installed remote access software.