This question is an exact duplicate of:
Background : Recently quora got breached and database were reported to be stolen, Myself used to have a habit of signing in through google login.
Problem statement : What were the possible impacts when i sign in through google authentication during database breach, In general whenever username and password is breached common implications will apply.But in the above case what can a black hat or bad guy can probably do.
Possible scene/Impact :
* Hacker can sign in using my oauth token ,but it requires valid session * Hacker can obtain my info through some api if website uses it.
What were the worst case will happen on above scenario,i.e when a database breach happens with third party authentication [google/openid,etc].Or we no need to worry at all?