Data flow integrity enforcement Runtime environment Optimizations Evaluation Conclusions

Data flow integrity enforcement overview Data flow integrity enforcement uses static analysis to computer a data flow graph. Program excute following such data – flow graph. Data flow integrity enforcement can be automatically applied to C & C++ without any mofification. It has no false positive and low overhead Compare other proposals to prevent attacks on software: • Its overhead is lower; • Not defend from attacks that overwrite specific targets or specific types of Vulnerabilities, but a broad class of attacks and prevent both control data attacks and non-control data attacks using data-flow integrity; • No false positives. TU Dresden, 04,Jun,2007 Securing software by enforcing data-flow integrity Folie 3 von 23 Generel technology about data-flow integrity enforcement How to ensure runtime data flow integrity? The implement uses reaching definitions analysis to compute a static data-flow graph to enforce data-flow integrity at runtime. Maintains a table with the identifier of the last instruction to write to each memory positon. Each memory position Identifier of the last instruction to write • Only compute the set of instructions that may write the value to low overhead and increase performance • We need check to make sure whether the value read from the table is computed by the static analysis or not. If not, we raise an exception • Update the table before every write • Prevent the attacker from tampering with the table TU Dresden, 04,Jun,2007 Securing software by enforcing data-flow integrity Folie 4 von 23 Reduce overhead Compute equivalence classes of instructions and assigns the same identifier to all the instructions in the same Class. Identifiers for different equivalence classes of instruction Different equivalence classes of instructio