Does A Breached Password Lookup Reveal My Password?
July 10, 2025
I had a discussion yesterday with an acquaintance about some new infostealer leaks; I was talking about verifying whether the credentials are new or not (which was a silly thing to do, I should have known they weren’t in HIBP — for different reasons though) and I went to check if some of the passwords were contained in the HIBP corpus. The acquiantance asked something to the effect of, “why would you put the password into a web form, isn’t that leaking it further?”. This naturally reveals a common misconception regarding how breached password lookups typically work; both in HIBP itself, and competing commercial breached corpuses.