JQF is a feedback-directed fuzz testing platform for Java, which uses the abstraction of property-based testing. JQF is built on top of junit-quickcheck: a tool for generating random arguments for parametric Junit test methods. JQF enables better input generation using coverage-guided fuzzing algorithms such as Zest.

Zest is an algorithm that biases coverage-guided fuzzing towards producing semantically valid inputs; that is, inputs that satisfy structural and semantic properties while maximizing code coverage. Zest's goal is to find deep semantic bugs that cannot be found by conventional fuzzing tools, which mostly stress error-handling logic only. By default, JQF runs Zest via the simple command: mvn jqf:fuzz.

JQF is a modular framework, supporting the following pluggable fuzzing front-ends called guidances:

• Binary fuzzing with AFL (tutorial)
• Semantic fuzzing with Zest [ISSTA'19 paper] (tutorial 1) (tutorial 2)
• Complexity fuzzing with PerfFuzz [ISSTA'18 paper]

JQF has been successful in discovering a number of bugs in widely used open-source software such as OpenJDK, Apache Maven and the Google Closure Compiler.

If you are using JQF in your research, we request you to cite our ISSTA'19 tool paper as follows:

Rohan Padhye, Caroline Lemieux, and Koushik Sen. 2019. JQF: Coverage-Guided Property-Based Testing in Java. In Proceedings of the 28th ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA ’19), July 15–19, 2019, Beijing, China. ACM, New York, NY, USA, 4 pages. https://doi.org/10.1145/3293882.3339002

Binary fuzzing tools like AFL and libFuzzer treat the input as a sequence of bytes. If the test program expects highly structured inputs, such as XML documents or JavaScript programs, then mutating byte-arrays often results in syntactically invalid inputs; the core of the test program remains untested.

Structured fuzzing tools leverage domain-specific knowledge of the input format to produce inputs that are syntactically valid by construction. Here is a nice article on structure-aware fuzzing of C++ programs using libFuzzer.

Structured fuzzing tools need a way to understand the input structure. Some other tools use declarative specifications of the input format such as context-free grammars or protocol buffers. JQF uses QuickCheck's imperative approach for specifying the space of inputs: arbitrary generator programs whose job is to generate a single random input.

A Generator<T> provides a method for producing random instances of type T. For example, a generator for type Calendar returns randomly-generated Calendar objects. One can easily write generators for more complex types, such as XML documents, JavaScript programs, JVM class files, SQL queries, HTTP requests, and many more -- this is generator-based fuzzing. However, simply sampling random inputs of type T is not usually very effective, since the generator does not know if the inputs that it produces are any good.

JQF supports the Zest algorithm, which uses code-coverage and input-validity feedback to bias a QuickCheck-style generator towards generating structured inputs that can reveal deep semantic bugs. JQF extracts code coverage using bytecode instrumentation, and input validity using JUnit's Assume API. An input is valid if no assumptions are violated.

• Zest 101: A basic tutorial for fuzzing a standalone toy program using command-line scripts. Walks through the process of writing a test driver and structured input generator for Calendar objects.
• Fuzzing a compiler with Zest: A tutorial for fuzzing a non-trivial program -- the Google Closure Compiler -- using a generator for JavaScript programs. This tutorial makes use of the JQF Maven plugin.
• Fuzzing with AFL: A tutorial for fuzzing a Java program that parses binary data, such as PNG image files, using the AFL binary fuzzing engine.

The JQF wiki contains lots more documentation including:

• Using a custom fuzz guidance
• Performance Benchmarks
• Bug trophy case

JQF also publishes its API docs.

We want your feedback! (haha, get it? get it?)

If you've found a bug in JQF or are having trouble getting JQF to work, please open an issue on the issue tracker. You can also use this platform to post feature requests.

If it's some sort of fuzzing emergency you can always send an email to the main developer: Rohan Padhye.