This document discusses big data security challenges and the application of user behavior analytics (UBA) to address those challenges. It first provides background on big data, defining its key characteristics and applications. It then outlines security risks to big data like privacy risks and risks to the data itself. Common big data security challenges are also summarized such as issues around data distribution, privacy, integrity and access control. The document then introduces UBA as a novel security analytics method, explaining how it uses machine learning to analyze user behaviors and detect anomalies that may indicate security threats like credential compromise or insider threats. Key advantages of UBA over other security tools are that it can more efficiently detect malicious user behavior and privileged account abuse.