Most probably that’s JUSTIN SUN’s minions doing the work. It doesn’t look like leaked passwords... how would they be able to hack so many people.... that’s not an accident
https://steemitwallet.com/@molly2/transfers
This the link for everyone to see. Like you said, this account is not active on hive yet.
I'm also thinking about that, but some active user in steemit is also affected so I choose to believe that an exploited dapp cause this.