Authentication is a mechanism to verify identity of users. Those who can present valid credential are considered as authenticated identities. In this paper, we introduce an adaptive authentication system called Unified Authentication Platform (UAP) which incorporates adaptive control to identify high-risk and suspicious illegitimate login attempts. The system evaluates comprehensive set of known information about the users from the past login history to define their normal behavior profile. The system leverages this information that has been previously stored to determine the security risk and level of assurance of current login attempt.