The exit state is constrained by a set of numeric constraints containing normal symbolic variables in programs and instrumented symbolic variables on the shapes. 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. An interpreter follows the program, assuming symbolic values for inputs rather than obtaining. Loop extended symbolic execution on binary programs. Section 4 gives our method for proving properties of java programs using symbolic execution and invariant generation and section 5 illustrates its application to the verification of several nontrivial java programs. The symbolic execution cannot identify of infeasible paths. The second issue is the invocation of any outofline code or module calls. We introduce loop extended symbolic execution, a generalization that broadens the coverage of symbolic results in programs with loops. On reaching a loop it iteratively solves the appropriate constraint system to find out which path through this loop to take, or, alternatively, whether to continue below the loop. You cant perfectly distribute aggegate properties of a program to individual statements. The problem is that even a single loop can generate a huge number of different symbolic execution paths, corresponding to different number of loop iterations.
Loopextended symbolic execution on binary programs request pdf. Loopextended symbolic execution on binary programs. Mixed concrete and symbolic execution is an important technique for finding and understanding software bugs, including securityrelevant ones. Symbolic execution is a successful technique used in software verification and.
Resolving loop based path explosion during symbolic execution shehbaz jaffer ashvin goel angela demke brown university of toronto abstract symbolic execution is a widely used method for testing device drivers and achieving high code coverage. On reaching a loop it iteratively solves the appropriate constraint system to find out which path through this loop to take, or, alternatively, whether to. Loopextended symbolic execution on binary programs eecs. And in this case in particular, the execution time property of a program cannot be reduced to the sum of execution times of individual statements. A survey on loop problems for dynamic symbolic execution dse is given in. Improving coverage of test cases generated by symbolic. Symbolic execution cannot proceed if the number of iterations in the loop is known. Several extensions to classical symbolic execution and stateoftheart tools are discussed.
One problem in exploring code using symbolic execution is loop based path explosion. A bibliography of papers related to symbolic execution saswatanandsymexbib. Loop invariant symbolic execution for parallel programs. Loop extended symbolic execution on list manipulating. Aug 30, 2016 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. While software analysis has been the subject of an extensive body of research in computer science, treatment of the topic in the control systems community has been less. Symbolic execution tree of function foobar given in figure 1. And in this case in particular, the execution time property of a program cannot be reduced to. Software security introducing symbolic execution youtube. Computing summaries of string loops in c for better testing.
We introduce loopextended symbolic execution, a generalization that broadens the coverage of symbolic results in programs with loops. Dynamic symbolic execution consists in executing the program, starting with arbitrary inputs, while performing a symbolic execution in parallel to collect sym. The symbolic execution also known as symbolic evaluation technique is a specific type of symbolic analysis of programs. It introduces symbolic variables for the number of times each loop executes, and links these with features of a known input grammar such as variablelength or repeating fields. This is the full version of the extended abstract to appear in. Loopextended symbolic execution on binary programs eecs at. Loops are challenging structures for program analysis, especially when loops contain multiple paths with complex interleaving executions among these paths. Efficient loop navigation for symbolic execution springerlink. Pdf loopextended symbolic execution on binary programs.
It introduces symbolic variables for the number of times each loop executes, and links these with features of a known input grammar such as variablelength or repeating. 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. Several sophisticated loop unrolling strategies proposed in literature aim at performing an informed guess on when no useful information could be extracted from the loop such as the loopextended symbolic execution lese saxena et al. Relating the number of iterations with features of the program. In proceedings of the eighteenth international sym posium on software testing and analysis, pages. A bibliography of papers related to symbolic execution github. Symbolic execution as empirical studies tool web application security checker enhancement to abstractionbased static analysis program synthesis tool all of these take advantage of. Jian zhang state key laboratory of computer science institute of software, chinese academy of sciences p.
In this article, we survey the main aspects of symbolic execution and discuss the most prominent. A good survey on symbolic execution for software testing is given in 2. Verification of java programs using symbolic execution and. Software security basic symbolic execution youtube. One of them is called concolic execution a portmanteau of concrete and symbolic execution or dynamic symbolic execution. In this article, we give an overview of modern symbolic execution techniques, discuss their key. We present cpasymexec, a tool for symbolic execution that is im. The problem is that even a single loop can generate a huge number of different symbolic execution paths, corresponding to different number of loop iterations and taking various paths through the loop.
Using dynamic symbolic execution to improve deductive. Dse executes the program using concrete random inputs and collects the path condition on the side. Box 8718, beijing 80, china 1 introduction for many decades, the correctness of programs has been a concern for computer scientists and software engineers. Section 4 gives our method for proving properties of java programs using symbolic execution and invariant generation and section 5 illustrates its application to the. It introduces symbolic variables for the number of times each loop executes, and links these with features of a known input grammar such. So i tapped to install the new software and after a little while got another notice that it had. Lese, our main contribution, enhances symbolic execution for directly inputdependent data values, as in singlepath. The idea is to enhance the symbolic execution with the utilization of quantitative aspect of the shape, and to construct the exit state of the loop. A survey of symbolic execution techniques season lab. However, existing symbolic execution techniques are limited to examining one execution path at a time, in which symbolic variables reflect only direct data dependencies. Symbolic execution the symbolic execution of a program is described in this section in an ideal sense, and then, in section 6, a particular practical system which has been built an ap proximation to the ideal is discussed.
Other forms of symbolic analysis of programs include bounded model checking which tools such as cbmc, escjava use and abstractionbased model checking which tools such as slam, blast use. Optimizing symbolic execution for malware behavior. Extended version, august 2011 3 2 system theoretic methods. At some point, symbolic execution will reach the edges of the application library, system, or assembly code calls in some cases, could pull in that code also e. We introduce loopextended symbolic execution, a generalization that broadens the coverage of symbolic results in programs withloops. Directed symbolic execution department of computer science. Several sophisticated loop unrolling strategies proposed in literature aim at performing an informed guess on when no useful information could be extracted from the loop such as the loop extended symbolic execution lese saxena et al. Since 1975 there has been references to this concept, but it has become more popular in the last ten years with the new smt solvers and evolved versions of symbolic execution. Citeseerx loopextended symbolic execution on binary. Softwareintheloop sil simulation represents the integration of compiled production source code into a mathematical model simulation, providing engineers with a practical, virtual simulation environment for the development and testing of detailed control strategies for large and complex systems. Resolving loop based path explosion during symbolic execution. A key limitation of symbolic execution is in dealing with code containing loops. Software inthe loop sil simulation represents the integration of compiled production source code into a mathematical model simulation, providing engineers with a practical, virtual simulation environment for the development and testing of detailed control strategies for large and complex systems.
I think symbolic execution can be used in many other interesting ways next. In this paper we propose a new symbolic execution technique, loopextended symbolic execution or lese for short, which gen. Symbolic execution is a successful and very popular technique used in software verification and testing. Techniques for verifying program assertions using symbolic execution exhibit a significant limitation. In this paper, we first propose a classification of multipath loops to understand the complexity of the loop execution, which is based on the variable updates on the loop conditions and the execution order of the loop paths. Each execution state, labeled with an upper case letter, shows the statement to be executed, the symbolic store. Dynamic symbolic execution for invariant inference. In this paper we propose a new symbolic execution technique, loopextended symbolic execution or. In proceedings of the 20 international conference on software engineering, icse, pages 212221, piscataway, nj, usa, 20. We propose a new type of symbolic execution, loop extended symbolic execution or lese, which captures the effects of more related program executions than just a single path as in singlepath symbolic execution, by modeling the effects of loops. Christoph csallner, nikolai tillmann, and yannis smaragdakis. Citeseerx loopextended symbolic execution on binary programs.
The technique infers a collection of constraint systems from the program and uses them to steer the symbolic execution towards the target. We introduce loop extended symbolic execution, a generalization that broadens the coverage of symbolic results in programs withloops. An interpreter follows the program, assuming symbolic values for inputs rather than obtaining actual inputs as normal execution of the program would. Prateek saxena, pongsin poosankam, stephen mccamant, and dawn song. In recent years, to maximize the value of software testing and analysis, we have proposed the methodology of cooperative software testing and analysis in short as cooperative testing and analysis to enable testing and analysis tools to cooperate with their users in the form of toolhuman cooperation, and enable one tool to cooperate with another tool in the form of tooltool cooperation. For sequential programs, there is a way to overcome this limitation using loop invariants. Many security and software testing applications require checking whether. Dawn song is a professor in the department of electrical engineering and computer science at uc berkeley.