Sensitive Data Leakage (SDL) is a major issue faced by organizations due to increasing reliance on data-driven decision-making. Existing Data Leakage Prevention (DLP) solutions are being challenged by the adoption of network transport encryption and the presence of privileged-mode malware designed to tamper with the DLP agent programs. We propose a novel DLP system called "HyperSweep" that uses Virtual Machine Memory Introspection (VMI) technology to inspect the memory content of a guest system for sensitive information. The approach is robust against both network transport encryption and malware that attack DLP agent programs. The HyperSweep prototype is implemented on top of the KVM hypervisor. Our experiments have confirmed its applicability to real-world applications, including web browsers, office applications, and social networking applications. The experiments also indicate moderate performance overhead from applying HyperSweep.