Abstract: Finding potential defects by statically detecting source code can help programmers find and fix the defects before the software is released,and thus can improve the security of the software．This paper provided a CIL static analysis method to detect defects in C# programs．We adopted an improved depth-first search algorithm to traverse the control flow graph of the target program,and combining with the strategy of caching history states,the performance of the detection can be greatly improved．In addition,to be convenient for alias analysis,we proposed a method based on Memory Region to represent variables．Based on the analysis method described in this paper,we developed a system for detecting defects in C# programs．We applied the system on real C# projects,and the detecting result shows that it can detect common kinds of defects in C# programs efficiently and accurately.

Key words: Static analysis,Defect detection,Alias analysis,CIL,C#