Cloud Computing has become the global technology enabler for corporate businesses and home users relying on IT services today. Cloud Computing offers unlimited flexible computing resources, storage and network capacity to seamlessly meet the service demands offering rental models, hosting options, virtual infrastructure, maximum utilization and availability. This exposes data and computing resources to external threats and cyber-attackers. To realize the full potential of Cloud Computing and to be successful, security threats and challenges need to be addressed and managed. To counter these attacks, Cloud service providers and organizations deploy firewalls and intrusion detection systems in data centers, while home users install antivirus and personal firewalls on desktops and laptops. This research focused primarily on designing a comprehensive, secure infrastructure architecture for mitigating the Distributed Denial of Service attacks on Hybrid Clouds, proposes Malware Detection solution to mitigate Ransomware attacks and reviewed algorithms for Cloud Security.