I believe there is a third party service that provides this type of verification. I don't know much about it by I've seen it many times (comes with applying for mortgages and other types of loans). I have gotten questions like "which of these streets have you lived on?" and "which of these banks issued you a credit card?" as well as "Which of these people do you know?" So I don't think it's necessarily Credit Karma's fault for asking you weird questions.

They have a direct relationship with Equifax and TransUnion, two of the major credit bureaus in the US. That is where the identity data comes from.

The first phase is to verify your identity by matching it against an authoritative data set, likely a credit file at either Equifax or TransUnion in this case. Once that data is matched, a set of questions from that data is generated. Your identity was likely matched against someone with similar identity information, hence the odd questions.

Do you a similar name to other people in your household? The good news is that the question set verifies you against the information it fetched. If you are not, you should fail the question set.

We at BlockScore provide an identity verification and question set service. Properly tuning the service to match the right person takes a lot of secret sauce because there is a lot of imperfect data. Thankfully we have this working well.

I signed up for CreditKarma too long ago to remember the process, but this is pretty standard for credit reporting services. I know Equifax, MyFICO, and the free annual government site do the same. In my experience the "You recently opened an auto loan..." questions are almost always answered with "none of the above".

Yeah, I've signed up for Equifax and MyFICO as well, and didn't have a problem with it. Maybe I just got "lucky" and stumbled on a bunch of really bizarre ones this time ;)

I didn't have problems signing up but according to them I have tax liens from before I was even born. I went to Experian directly and they don't exist (nor have I ever heard/seen such). Maybe they are trying to be cute with data and supplement it?

If you don't have enough info in your credit report to ask enough questions of course they have to supplement it. you would presumably still know the answers since you'd know if you have a loan or not.

Sounds like a typical out of wallet type service. For Developers there's BlockScore, but the most used one is probably Experian's.

Likely TransUnion or Equifax since CreditKarma has direct relationships.