skip to main content

Title: Saffron: Adaptive Grammar-based Fuzzing for Worst-Case Analysis.
Fuzz testing has been gaining ground recently with substantial efforts devoted to the area. Typically, fuzzers take a set of seed inputs and leverage random mutations to continually improve the inputs with respect to a cost, e.g. program code coverage, to discover vulnerabilities or bugs. Following this methodology, fuzzers are very good at generating unstructured inputs that achieve high coverage. However fuzzers are less effective when the inputs are structured, say they conform to an input grammar. Due to the nature of random mutations, the overwhelming abundance of inputs generated by this common fuzzing practice often adversely hinders the effectiveness and efficiency of fuzzers on grammar-aware applications. The problem of testing becomes even harder, when the goal is not only to achieve increased code coverage, but also to nd complex vulnerabilities related to other cost measures, say high resource consumption in an application. We propose Saffron an adaptive grammar-based fuzzing approach to effectively and efficiently generate inputs that expose expensive executions in programs. Saffron takes as input a user-provided grammar, which describes the input space of the program under analysis, and uses it to generate test inputs. Saffron assumes that the grammar description is approximate since precisely describing the input program more » space is often difficult as a program may accept unintended inputs due to e.g., errors in parsing. Yet these inputs may reveal worst-case complexity vulnerabilities. The novelty of Saffron is then twofold: (1) Given the user-provided grammar, Saffron attempts to discover whether the program accepts unexpected inputs outside of the provided grammar, and if so, it repairs the grammar via grammar mutations. The repaired grammar serves as a specification of the actual inputs accepted by the application. (2) Based on the refined grammar, it generates concrete test inputs. It starts by treating every production rule in the grammar with equal probability of being used for generating concrete inputs. It then adaptively refines the probabilities along the way by increasing the probabilities for rules that have been used to generate inputs that improve a cost, e.g., code coverage or arbitrary user-defined cost. Evaluation results show that Saffron significantly outperforms state-of-the-art baselines. « less
Authors:
; ; ; ; ;
Award ID(s):
1901136
Publication Date:
NSF-PAR ID:
10149230
Journal Name:
ACM SIGSOFT Software Engineering Notes
Sponsoring Org:
National Science Foundation
More Like this
  1. Concolic testing combines concrete execution with symbolic execution along the executed path to automatically generate new test inputs that exercise program paths and deliver high code coverage during testing. The GKLEE tool uses this approach to expose data races in CUDA programs written for execution of GPGPUs. In programs employing concurrent dynamic data structures, automatic generation of data structures with appropriate shapes that cause threads to follow selected, possibly divergent, paths is a challenge. Moreover, a single non-conflicting data structure must be generated for multiple threads, that is, a single shape must be found that simultaneously causes all threads to follow their respective chosen paths. When an execution exposes a bug (e.g., a data race), the generated data structure shape helps the programmer understand the cause of the bug. Because GKLEE does not permit pointers that construct dynamic data structures to be made symbolic, it cannot automatically generate data structures of different shapes and must rely on the user to write code that constructs them to exercise desired paths. We have developed DSGEN for automatically generating non-conflicting dynamic data structures with different shapes and integrated it with GKLEE to uncover and facilitate understanding of data races in programs that employmore »complex concurrent dynamic data structures. In comparison to GKLEE, DSGEN increases the number of races detected from 10 to 25 by automatically generating a total of 1,897 shapes in implementations of four complex concurrent dynamic data structures -- B-Tree, Hash-Array Mapped Trie, RRB-Tree, and Skip List.« less
  2. As big data analytics become increasingly popular, data-intensive scalable computing (DISC) systems help address the scalability issue of handling large data. However, automated testing for such data-centric applications is challenging, because data is often incomplete, continuously evolving, and hard to know a priori. Fuzz testing has been proven to be highly effective in other domains such as security; however, it is nontrivial to apply such traditional fuzzing to big data analytics directly for three reasons: (1) the long latency of DISC systems prohibits the applicability of fuzzing: naïve fuzzing would spend 98% of the time in setting up a test environment; (2) conventional branch coverage is unlikely to scale to DISC applications because most binary code comes from the framework implementation such as Apache Spark; and (3) random bit or byte level mutations can hardly generate meaningful data, which fails to reveal real-world application bugs. We propose a novel coverage-guided fuzz testing tool for big data analytics, called BigFuzz. The key essence of our approach is that: (a) we focus on exercising application logic as opposed to increasing framework code coverage by abstracting the DISC framework using specifications. BigFuzz performs automated source to source transformations to construct an equivalent DISCmore »application suitable for fast test generation, and (b) we design schema-aware data mutation operators based on our in-depth study of DISC application error types. BigFuzz speeds up the fuzzing time by 78 to 1477X compared to random fuzzing, improves application code coverage by 20% to 271%, and achieves 33% to 157% improvement in detecting application errors. When compared to the state of the art that uses symbolic execution to test big data analytics, BigFuzz is applicable to twice more programs and can find 81% more bugs.« less
  3. While many real-world programs are shipped with configurations to enable/disable functionalities, fuzzers have mostly been applied to test single configurations of these programs. In this work, we first conduct an empirical study to understand how program configurations affect fuzzing performance. We find that limiting a campaign to a single configuration can result in failing to cover a significant amount of code. We also observe that different program configurations contribute differing amounts of code coverage, challenging the idea that each one can be efficiently fuzzed individually. Motivated by these two observations, we propose ConfigFuzz , which can fuzz configurations along with normal inputs. ConfigFuzz transforms the target program to encode its program options within part of the fuzzable input, so existing fuzzers’ mutation operators can be reused to fuzz program configurations. We instantiate ConfigFuzz on six configurable, common fuzzing targets, and integrate their executions in FuzzBench. In our evaluation, ConfigFuzz outperforms two baseline fuzzers in four targets, while the results are mixed in the other targets due to program size and configuration space. We also analyze the options fuzzed by ConfigFuzz and how they affect the performance.
  4. Coverage-guided fuzzing has become mainstream in fuzzing to automatically expose program vulnerabilities. Recently, a group of fuzzers are proposed to adopt a random search mechanism namely Havoc, explicitly or implicitly, to augment their edge exploration. However, they only tend to adopt the default setup of Havoc as an implementation option while none of them attempts to explore its power under diverse setups or inspect its rationale for potential improvement. In this paper, to address such issues, we conduct the first empirical study on Havoc to enhance the understanding of its characteristics. Specifically, we first find that applying the default setup of Havoc to fuzzers can significantly improve their edge coverage performance. Interestingly, we further observe that even simply executing Havoc itself without appending it to any fuzzer can lead to strong edge coverage performance and outperform most of our studied fuzzers. Moreover, we also extend the execution time of Havoc and find that most fuzzers can not only achieve significantly higher edge coverage, but also tend to perform similarly (i.e., their performance gaps get largely bridged). Inspired by the findings, we further propose Havoc𝑀𝐴𝐵, which models the Havoc mutation strategy as a multi-armed bandit problem to be solved by dynamicallymore »adjusting the mutation strategy. The evaluation result presents that Havoc𝑀𝐴𝐵 can significantly increase the edge coverage by 11.1% on average for all the benchmark projects compared with Havoc and even slightly outperform state-of-the-art QSYM which augments its computing resource by adopting three parallel threads. We further execute Havoc𝑀𝐴𝐵 with three parallel threads and result in 9% higher average edge coverage over QSYM upon all the benchmark projects« less
  5. Grammar-based fuzzing is a technique used to find soft- ware vulnerabilities by injecting well-formed inputs generated following rules that encode application semantics. Most grammar-based fuzzers for network protocols rely on human experts to manually specify these rules. In this work we study automated learning of protocol rules from textual specifications (i.e. RFCs). We evaluate the automatically extracted protocol rules by applying them to a state-of-the-art fuzzer for transport protocols and show that it leads to a smaller number of test cases while finding the same attacks as the system that uses manually specified rules.