Software security basic symbolic execution youtube. Postconditioned symbolic execution ieee conference. Instead of using concrete inputs, symbolic execution executes a program with symbolic inputs. The experimental results show that these techniques can signi. Basic symbolic execution program analysis coursera. Deconstructing dynamic symbolic execution microsoft research. We have implemented a software tool based on the klee. Third chapter, toolchain and case study preparation, covers work done on klee, emotor software and the macan library in the course of writing my thesis. Watson research center this paper describes the symbolic execution of pro grams. Symbolic execution wei le thank cristian cadar, patrice godefroid, je foster, nikolai tillmann, vijay ganesh for some of the slides 2014. Eliminating path redundancy via postconditioned symbolic execution. Symbolic execution and software testing part 1 corina pasareanu cmu silicon valley nasa ames research center nato international summer school 2012. Incremental symbolic execution of concurrent software faculty. Prior regression testing tools focus mainly on test case selection and prioritization whereas symbolic execution.
However, its practical usage is often limited by the pat. A well known problem with symbolic execution is the path explosion problem. I symbolic execution is the key technique used in darpa cyber grand challenge. While some regression testing tools can leverage code changes between two software ver. Pasareanu2, willem visser3 1 college of computing, georgia institute of technology email. Yufeng zhang, zhenbang chen, ji wang, wei dong, and zhiming liu. During symbolic execution, program state consists of symbolic values for some memory locations. We have implemented our method in the symbolic execution engine klee.
Popular for nding software bugs and vulnerabilities. So lets return to the idea of concolic execution i mentioned before, this is also called dynamic symbolic execution sometimes. Symbolic execution symbolic execution is a software testing technique that is useful to aid the generation of test data and in proving the program quality. One of the main challenges of symbolic execution is the path explosion problem. Verlag 2009 abstract symbolic execution is a wellknown program analysis technique which represents program inputs with symbolic values instead of concrete, initialized, data and. In computer science, symbolic execution also symbolic evaluation is a means of analyzing a program to determine what inputs cause each part of a program to execute. Postconditioned symbolic execution can identify path suf. In contrast, postconditioned symbolic execution has a path coverage that is equivalent to standard symbolic execution, because the dynamically computed postconditions eliminate redundant paths only. Symbolic execution as search, and the rise of solvers. Such vulnerabilities allow an attacker to mount denial. A survey of new trends in symbolic execution for software testing and analysis article in international journal on software tools for technology transfer 114. We have implemented a software tool based on the klee symbolic virtual machine 1 and evaluated it.
Article in international journal on software tools for technology transfer. Importantly, we take a build security in mentality, considering techniques at each phase of the development cycle that can be used to strengthen the security of software systems. Efficient symbolic execution for software testing johannes kinder royal holloway, university of london joint work with. A survey of symbolic execution techniques season lab. Test inputs are chosen based on whether they can trigger new branching behaviors of the program. I think symbolic execution can be used in many other interesting ways next. The execution requires a selection of paths that are exercised by a set of data values. At each branching location, in addition to determine whether a particular branch is feasible as in traditional symbolic execution, our approach checks whether the branch is subsumed by previous explorations. Each execution state, labeled with an upper case letter, shows the statement to be executed, the symbolic store.
Dynamic symbolic execution visual studio microsoft docs. Eliminating path redundancy via postconditioned symbolic. Symbolic execution is a program analysis technique introduced in the 70s that has received renewed interest in recent years, due to algorithmic advances and increased availability of computational power and constraint solving technology. Symbolic execution with interpolation is emerging as an alternative to cegar for software veri. It provides a powerful analysis in principle but remains challenging to scale and generalize symbolic execution in practice. We propose several optimization heuristics to reduce its cost. Intellitest generates inputs for parameterized unit tests by analyzing the branch conditions in the program. Symbolic execution and program testing people at vt. Various means, such as symbolic execution, concolic execution, taint analysis, can be used in binary analysis to help collect control flow information, execution path information, etc. In this article, we survey the main aspects of symbolic execution and discuss the.
Qiuping yi, zijiang yang, shengjian guo, chao wang, jian liu, and chen zhao. During execution, a symbolic execution engine accumulates a set of constraints on the symbolic inputs. We have developed symbolic java pathfinder, a symbolic execution framework that implements a nonstandard bytecode interpreter on top of the java pathfinder model checking tool. Parallel symbolic execution for automated realworld. Dynamic symbolic execution dse is a wellknown technique for automatically generating tests to achieve higher levels of coverage in a program. Klee is a symbolic virtual machine built on top of the llvm compiler infrastructure, and available under the uiuc open source license. Symbolic execution is a systematic technique for checking programs, which forms a basis for various software testing and verification techniques. For more information on what klee is and what it can do, see the osdi 2008 paper. We describe techniques based on symbolic execution for finding software vulnerabilities that are due to algorithmic complexity. In proceeding of the 2018 26th acm joint meeting on european software engineering conference and symposium on the foundations of software engineeringesecfse, fl, usa.
Dependence guided symbolic execution ieee transactions on. To mitigate the path explosion problem, we propose a new redundancy removal method called postconditioned symbolic execution. Dec 09, 20 software testingdebugging is extremely time consuming, and hence techniques to automate debugging or program repair are of value. Assertion guided symbolic execution of multithreaded programs. Some insights about symbolic execution i execute programs with symbols. In software testing, symbolic execution is used to generate a test input for each feasible execution path of a program. Hotspot symbolic execution of floatingpoint programs minghui quan acm sigsoft international symposium on foundations of software engineering fse 2016 november 18, 2016, seattle, wa, usa. Symbolic execution is a powerful technique for systematic testing of sequential and multithreaded programs. A generic framework for symbolic execution universitatea. But because most programs have a huge number of paths we cant usually run symbolic execution. Role of symbolic execution in software testing, debugging and. Finding bios vulnerabilities with symbolic execution and. Selecta formal system for testing and debugging programs by symbolic execution. A survey of symbolic execution techniques acm computing.
Klee llvm execution engine klee is a symbolic virtual machine built on top of the llvm compiler infrastructure, and available under the uiuc open source license. Ieee international conference on software testing, verification and validation. Software tools for technology transfer manuscript no. Symbolic execution tree of function foobar given in figure 1. Symbolic execution is a wellknown program analysis technique which represents program inputs with symbolic values instead of concrete, initialized, data and executes the program by manipulating program expressions involving the symbolic values. Abstract symbolic execution is a wellknown program analysis technique which represents program inputs with symbolic values instead of concrete, initialized, data and. Eliminating path redundancy via postconditioned symbolic execution qiuping yi, zijiang yang, shengjian guo, chao wang, jian liu, chen zhao. Abstractcompositional symbolic execution has been pro posed as a way to.
Enhancing dynamic symbolic execution by automatically. Generalized symbolic execution for model checking and testing sarfraz khurshid1, corina s. Postconditioned symbolic execution can identify path suffixes shared by multiple runs and eliminate them during test generation when they are redundant. This paper presents the basics of the symbolic execution approach and studies the common tools which utilize symbolic execution in them. Symbolic execution is a software testing technique that is useful to aid the generation of test data and in proving the program quality. Qiuping yi, zijiang yang, shengjian guo, chao wang, jian liu and chen zhao.
Parallel symbolic execution for automated realworld software testing stefan bucur vlad ureche cristian zam. An interpreter follows the program, assuming symbolic values for inputs rather than obtaining actual inputs as normal execution of the program would. Essentially, for a symbolic executor to consider the entirety programs space of executions it needs to consider every path. A survey of new trends in symbolic execution for software testing and analysis. We present cpasymexec, a tool for symbolic execution that is im plemented in the. Abstract symbolic execution is a powerful technique for systematically exploring the paths of a program and generating the corresponding test inputs. Complexity vulnerability analysis using symbolic execution.
In proceedings of the 2015 ieee 8th international conference on software testing, verification and validation icst15. Rajan fujitsu labs of america, ca gli, ighosh, sree. Introduction to symbolic execution with angr jc duration. Symbolic execution is emerging as a powerful technique for generating test inputs systematically to achieve exhaustive path coverage of a bounded depth. Parallel symbolic execution for automated realworld software. Instead of supplying the normal inputs to a program e. And the idea here is, instead of running the program according to the algorithm that we just saw a moment ago, we run the program concretely, but we instrument it to sort of do symbolic execution on the side. Symbolic execution symbolic execution refers to execution of program with symbols as argument. Symbolic execution georgia institute of technology.
Three decades later cristian cadar imperial college london c. Software testingdebugging is extremely time consuming, and hence techniques to automate debugging or program repair are of value. Symbolic execution is a popular program analysis technique introduced in the mid. An interpreter follows the program, assuming symbolic values for inputs rather than obtaining actual inputs as normal execution. If the correctness criteria for the given program is described by a set of test cases, we will show that. This dissertation evaluates the proposed methods on a diverse set of both synthesized programs and realworld applications. Symbolic execution a program analysis technique that executes a program with symbolic rather than concrete input values. Symbolic execution for software testing in practice. Postconditioned symbolic execution ieee conference publication. Symbolic execution with abstraction stanford university. Regular property guided dynamic symbolic execution.
As a result, the output values computed by a program are expressed as a function of the input symbolic values. Symbolic execution as empirical studies tool web application security checker enhancement to abstractionbased static analysis program synthesis tool all of these take advantage of sym exec strengths, and try to avoid drawbacks 7. Software security introducing symbolic execution youtube. Dependence guided symbolic execution ieee transactions. Pruning away such redundant paths can lead to a potentially exponential reduction in the number of explored paths. The use of symbolic execution for testing of realtime. However, its practical usage is often limited by the path explosion problem, that is, the number of explored paths usually grows exponentially with. However, its application is limited by the high cost of covering all feasible intrathread paths and interthread interleavings. Compositional symbolic execution using finegrained summaries. We propose a new symbolic execution method for identifying and eliminating redundant path suf. Klee is a symbolic virtual machine built on top of the llvm compiler infrastructure. Generalized symbolic execution for model checking and testing. Generating performance distributions via probabilistic symbolic execution bihuan chen, yang liu and wei ley school of computer engineering, nanyang technological university, singapore ydepartment of computer science, iowa state university, usa abstract. Generating performance distributions via probabilistic.
Unlike concrete execution, where the taken path is determined by the input, in symbolic execution the program can take any feasible path. Eliminating path redundancy via postconditioned symbolic execution article in ieee transactions on software engineering pp99. A survey of new trends in symbolic execution for software. Postconditioned symbolic execution is computational expensive. Symbolic analysis and test generation symbolic execution is a powerful technique to systematically explore paths possibly all of a software program. Many security and software testing applications require checking whether certain. A survey of new trends in symbolic execution for software testing.
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