Fuzzing

Introducing Medusa v1, a cutting-edge fuzzing framework designed to enhance smart contract security.

Fuzzing—one of the most successful techniques for finding security bugs, consistently featured in articles and industry conferences—has become so popular that you may think most important software has already been extensively fuzzed. But that’s not always the case. In this blog post, we show how we fuzzed the ZBar barcode scanning library […]

Fuzzing—a testing technique that tries to find bugs by repeatedly executing test cases and mutating them—has traditionally been used to detect segmentation faults, buffer overflows, and other memory corruption vulnerabilities that are detectable through crashes. But it has additional uses you may not know about: given the right invariants, we can use […]

This post will guide you through using AddressSanitizer (ASan), a compiler plugin that helps developers detect memory issues in code that can lead to remote code execution attacks (such as WannaCry or this WebP implementation bug). ASan inserts checks around memory accesses during compile time, and crashes the program […]

During my time as a Trail of Bits associate last summer, I worked on optimizing the performance of Echidna, Trail of Bits’ open-source smart contract fuzzer, written in Haskell. Through extensive use of profilers and other tools, I was able to pinpoint and debug a massive space leak in one of Echidna’s […]

Welcome to our deep dive into the world of invariant development with Curvance. We’ve been building invariants as part of regular code review assessments for more than 6 years now, but our work with Curvance marks our very first official invariant development project, in which developing and testing invariants is all we […]

Trail of Bits is excited to introduce Ruzzy, a coverage-guided fuzzer for pure Ruby code and Ruby C extensions. Fuzzing helps find bugs in software that processes untrusted input. In pure Ruby, these bugs may result in unexpected exceptions that could lead to denial of service, and in Ruby C extensions, they […]

We recently introduced our new offering, invariant development as a service. A recurring question that we are asked is, “Why fuzzing instead of formal verification?” And the answer is, “It’s complicated.” We use fuzzing for most of our audits but have used formal verification methods in the […]

Near the end of 2022, Trail of Bits was hired by the Open Source Technology Improvement Fund (OSTIF) to perform a security assessment of the cURL file transfer command-line utility and its library, libcurl. The scope of our engagement included a code review, a threat model, and the subject of this blog […]

Deserializing, decoding, and processing untrusted input are telltale signs that your project would benefit from fuzzing. Yes, even Python projects. Fuzzing helps reduce bugs in high-assurance software developed in all programming languages. Fortunately for the Python ecosystem, Google has released Atheris, a coverage-guided fuzzer for both pure Python code and Python C […]

Our latest addition to the Trail of Bits Testing Handbook is a comprehensive guide to fuzzing: an essential, effective, low-effort method to find bugs in software that involves repeatedly running a program with random inputs to cause unexpected results. At Trail of Bits, we don’t just rely on standard static analysis. We tailor our approach […]

Cosmos is a platform enabling the creation of blockchains in Go (or other languages). Its reference implementation, Cosmos SDK, leverages strong fuzz testing extensively, following two approaches: smart fuzzing for low-level code, and dumb fuzzing for high-level simulation. In this blog post, we explain the differences between these approaches and show how […]

Last month, two of our engineers attended the 37th Chaos Communication Congress (37C3) in Hamburg, joining thousands of hackers who gather each year to exchange the latest research and achievements in technology and security. Unlike other tech conferences, this annual gathering focuses on the interaction of technology and society, covering such topics as politics, entertainment, […]

With the release of version 2.1.0 of Echidna, our fuzzing tool for Ethereum smart contracts, we’ve introduced new features for direct retrieval of on-chain data, such as contract code and storage slot values. This data can be used to fuzz deployed contracts in their on-chain state or to test […]

In fall 2022, Trail of Bits audited cURL, a widely-used command-line utility that transfers data between a server and supports various protocols. The project coincided with a Trail of Bits maker week, which meant that we had more manpower than we usually do, allowing us to take a nonstandard approach to the […]