Dynamic Taint Analysis for Automatic Detection, Analysis,and 分析自动检测，动态污点分析，和.ppt

Dynamic Taint Analysis for Automatic Detection, Analysis, and Signature Generation of Exploits on Commodity Software Paper by: James Newsome and Dawn Song Network and Distributed Systems Security Symposium (NDSS), Feb 2005. Presented by: Devendra Salvi 03/22/2007 Outline Motivation Dynamic Taint analysis Evaluation Application Review Motivation Worms exploit software vulnerabilities like, buffer overrun and “format string” vulnerability For a new attack, attack signatures should be developed automatically. Motivation (contd.) Attack detectors are Coarse grained detectors Detect anomalous behavior and do not provide detailed information about the vulnerability Fine grained detectors Detect attacks on programs vulnerabilities and hence provide detailed information about the attack Dynamic taint analysis Mark input data as “tainted” Monitor program execution to track how tainted attributes propagate Check when tainted data is used in dangerous ways Dynamic taint analysis TaintCheck performs dynamic taint analysis on a program by running the program in its own emulation environment. Dynamic taint analysis Dynamic taint analysis TaintSeed It marks any data from untrusted sources as “tainted” Each byte of memory has a four-byte shadow memory that stores a pointer to a Taint data structure if that location is tainted, or a NULL pointer if it is not. Dynamic taint analysis TaintTracker It tracks each instruction that manipulates data in order to determine whether the result is tainted. When the result of an instruction is tainted by one of the operands, TaintTracker sets the shadow memory of the result to point to the same Taint data structure as the tainted operand. Dynamic taint analysis TaintAssert It checks whether tainted data is used in ways that its policy defines as illegitimate. Dynamic taint analysis Exploit Analyzer The Exploit Analyzer can provide useful information about how the exploit happened, and what the exploit attempts to do. Dynamic