The Internet is constantly evolving, producing many new data sources that can be used to help us gain insights into the cyber threat landscape and in turn, allow us to better prepare for cyberattacks. With this in mind, we present an end-to-end real-time cyber situational awareness system which aims to retrieve security-relevant information from the social networking site Twitter.com. This system classifies and aggregates the data extracted and provides real-time cyber situational awareness information based on sentiment analysis and data analytics techniques. This research will assist security analysts in rapidly and efficiently evaluating the level of cyber risk in their organization and allow them to proactively take actions to plan and prepare for potential attacks before they happen.