They aren’t sure yet if someone else found it first. If a smart person found it first they could sell it piecemeal to make it harder to know where it came from. Each identity isn’t worth much but that’s a lot. Combine that with the password stuffing capability from a plain text password list and there’s…
If you ever, ever store passwords in plain text instead of hashed and salted your business should be shut down. Thats below even Security 101 level, and shows a critical carelessness for user data.
When we’re find things like this, unless we have exact audit logs proving there was no misuse, we assume it was misused because that’s the only sane way to do it.
If it turns out they have excellent logging (hah) maybe they can prove it, let’s hope so for the affected people’s sake.