High-level semantic vulnerabilities such as SQL injection and crosssite scripting have surpassed buffer overflows as the most prevalent security exploits. The breadth and diversity of software vulnerabilities demand new security solutions that combine the speed and practicality of hardware approaches with the flexibility and robustness of software systems. This paper proposes Raksha, an architecture for software security based on dynamic information flow tracking (DIFT). Raksha provides three

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... vel features that allow for a flexible hardware/software approach to security. First, it supports flexible and programmable security policies that enable software to direct hardware analysis towards a wide range of high-level and low-level attacks. Second, it supports multiple active security policies that can protect the system against concurrent attacks. Third, it supports low-overhead security handlers that allow software to correct, complement, or extend the hardware-based analysis without the overhead associated with operating system traps. We present an FPGA prototype for Raksha that provides a fullfeatured Linux workstation for security analysis. Using unmodified binaries for real-world applications, we demonstrate that Raksha can detect high-level attacks such as directory traversal, command injection, SQL injection, and cross-site scripting as well as low-level attacks such as buffer overflows. We also show that lowoverhead exception handling is critical for analyses such as memory corruption protection in order to address false positives that occur due to the diverse code patterns in frequently used software.