The present disclosure relates to knowledge based authentication whereby a user is authenticated through third-party linked accounts. The method includes receiving an authentication request from a merchant computer, assessing one or more data fields to generate an authentication challenge for the user, connecting to one or more third-party account service provider to extract user-related data, generating the authentication challenge based on the extracted user-related data from the third-party account service provider, posing the authentication challenge to the user on a user device, receiving a response to the authentication challenge, and returning the authentication response to the merchant.