Diligence Blog

It’s been a couple of years since code4rena has introduced competitive audits into the smart contract security landscape, and it looks like audit contests are here to stay. In the meanwhile several other platforms have popped up with the same forumula. Audit contests are simple. A project publishes a set of smart contracts that they would like to have audited, and promises a prize pool for security related findings. A contest is ran for a couple of weeks during which participants can submit their findings.

We recently released a new tool called napalm, a detection module IDE. Napalm makes it easy to set-up a multi-tool custom detector project. Not stopping there, napalm provides an all-out quality of life upgrade for security researchers that like to write their own detection modules. A tool that helps you develop detection modules is great, but it occurred to me that lots of people are not writing their own detection modules yet.

Attention, all auditors and security researchers! We’ve got a new tool for you! You’re a security researcher and you hate repetitive work. So what do you do? You’ve compiled a nice collection of analysis rules and detection modules that automatically do all the repetitive work for you. Life is great, until, …. You’ve got 100+ modules, some for slither, others for semgrep and things are getting out of hand! You have to spend time writing scripts to run the right modules at the right time, and it’s impossible to even keep track of what you can automatically detect.

Enterprise Ethereum Alliance (EEA) shapes the most mature standard for smart contract security. Consensys Diligence contributes to the EthTrust Security Levels Specification, spearheaded by the EEA EthTrust Security Levels Working Group.

Learn how an audit by the Diligence team made GLIF’s smart contracts and protocol more secure.

This blog post discusses Tidal’s engagement with Consensys Diligence to audit the protocol’s on-chain insurance smart contracts.

Consensys Diligence provides actionable tips on building secure and robust smart contracts in web3.

On May 6th 2023 DeusDao was exploited resulting in $6.5M in losses. A detailed write-up of the event can be found here. The root cause of the exploit, was a logical error in the burnFrom function. function burnFrom(address account, uint256 amount) public virtual { uint256 currentAllowance = _allowances[_msgSender()][account]; _approve(account, _msgSender(), currentAllowance - amount); _burn(account, amount); } On the first line of burnFrom, the message sender and account are accidentally swapped when computing the allowance for tokens to burn.

Announcing Diligence Fuzzing support for all Foundry developers to ensure easy and efficient smart contract security.

Consensys Diligence explains the Halo2 zero-knowledge prover and highlights bugs that can affect security of Halo2 circuits.

Crypto hacks are costing projects millions in user funds. Bug bounty programs can help prevent exploits and secure the Web3 ecosystem. Bug bounties provide financial incentives for hackers and researchers to disclose flaws in applications to development teams. In the tech industry, where minor software errors can lead to catastrophic losses, bug bounties provide a cost-effective method for detecting vulnerabilities in code. Bug bounties have a long history: In 1983, microprocessor manufacturer Hunter & Ready launched the “Bug for a Bug” program—finding flaws in its VRTX operating system earned the finder a Volkswagen Beetle, commonly called the “Bug”.

An overview of the emerging web3 security stack and industry.

While smart contract systems of today have the capability to be deployed with permissions, upgradeable proxies, and ways to add extra logic to them, the unique selling point of this technology has always been its ability to remain immutable and predictable after the initial deployment. Systems with these properties can be used reliably by integrators with strong expectations that they will continue working as expected. From a smart contract security perspective, this allows users and builders to rest easy knowing that the code they are transacting with now will not change and surprise them.

Helping users with selecting a suitable fuzzer

Use this helpful checklist to prepare your smart contacts for an audit

Step-by-step tutorial to get started using Fuzzing for your smart contract security

Diligence Fuzzing is now available for developers for testing smart contract systems.

How you can record fuzzing lessons in Diligence Fuzzing

In 2021 we privately disclosed multiple vulnerabilities in the InterPlanetary File System but never really talked about it. Let’s change that 😊!

Earlier this year, ConsenSys Diligence announced its partnership with StarkWare to expand its security audit capabilities for smart contracts written in Cairo and deployed on StarkWare. “We were very impressed by the team’s in-depth analysis and understanding of Cairo, overcoming the fact that this is a new language. Consensys Diligence has already contributed to the safety of StarkEx by detecting a bug that was promptly fixed.” said Uri Kolodny, Co-founder and CEO at StarkWare about the partnership.

These four features make Scribble a more expressive specification language to help make testing your smart contract simpler.

A look at the state of the blockchain security industry and our plans in 2022.

Learn how provers can exploit under-constrained Cairo programs! Introduction Cairo is a programming language for building zero-knowledge programs. These programs allow you to prove the result of a computation without asking other people to re-run the computation. Proofs of correct computation are awesome! Let’s assume you have a Cairo program to compute all prime numbers up to 1,000. When you run Cairo, you’ll get both the prime numbers and proof that those prime numbers are the result of running the program.

Buidling, breaking, hacking, making! 🥷⚔️ Testing boundaries and playing with experimental technology is what we love at Diligence. In this spirit, “HackWek” was born. A recurring Diligence internal five-day hacking party 🥳. In this episode, I set out building a Solidity source code writing robot 😵‍💫🤖. Hallucinating Solidity Source Code Some time ago I’ve started to collect smart contract samples from public block explorers with the smart-contract-sanctuary project. Initially, for no special reason, but it quickly turned into a treasure trove for all kinds of activities.

Fuzzing ERC20 contracts Learn how you can use Scribble to define a complete and checkable ERC20 specification. As a bonus, we show how you can use fuzzing to check the specification automatically! I’m willing to bet that you’re familiar with the ERC20 standard, the best-known standard for tokens (next to ERC721). You might be less familiar with Scribble and fuzzing, which provide the easiest way to test ERC20 implementations exhaustively.

The ConsenSys Diligence team has built a lot of tools with use cases ranging from automatic vulnerability discovery (check out MythX) to network-based vulnerability scanning (TeaTime), to code understanding tools (Surya, VSCode visual developer). Check out all our tools here: Blockchain Security Tools | ConsenSys Diligence A few months ago, we released Scribble, an all-new specification language for smart contracts. Using Scribble, you can extend your smart contract with specifications that we can automatically check using fuzzing and symbolic execution techniques.

Since we released Scribble last December, we have been hard at work adding new features to the language and the tool itself. In this series of posts, we will look at some of the new features we’ve added. Our first post showcases state variable annotations with if_updated. The problem During our early usage of Scribble it became apparent that annotations of functions and contracts are nice, but are sometimes insufficient when reasoning about individual state variables.

There’s nothing more enjoyable than gathering a group of friends, eating pizza, and hack on something you’ve always wanted to build but haven’t had time for. When we learned that ConsenSys is organizing an internal hackathon, it didn’t take us long to find projects to hack on. A couple of friends started hacking on “TURN”, a revolutionary token-based solution that could simplify our day-to-day operations. More on this in a future post.

Some vendors use an effective sales strategy called “lock-in”. Once you’re in the vendors’ ecosystem, it can be challenging to get out. You’ll have made a big investment into various products that work great together but suck once you use them with anything else. A similar thing can happen (often unintentionally) with tech stacks. You invest big-time in tool X and are then locked into using it because you don’t want to start from scratch with a new tool Y.

TL;DR: Path-based IPFS gateways have a critical flaw: They effectively disable one of the essential security features of modern browsers: the same-origin policy. Note Update: June 16, 2021 We’d like to thank the team at security[at]ipfs.io for picking up and addressing our concerns. It is a pleasure seeing security being taken seriously and we’d like to share their updates and feedback with you. The following statements were provided by the IPFS security team and have not been validated by Consensys Diligence.

Writing Smart Contracts can be fraught with dangers stemming from multiple vectors, but one you may not have considered is Cross Site Scripting attacks initiated by the Smart Contract itself! How is this possible? Let’s explore and solve.

ConsenSys Diligence team, a.k.a Dilicious, won the first place at Paradigm Capture the Flag competition. Paradigm CTF was one of the most anticipated security competitions in the Ethereum space.

Sometimes unit-tests fail, and you don’t know why. That’s when you want to use fault localisation; to find the fault that’s causing the tests to fail. Tarantula is such an algorithm and finds which lines are most suspect of breaking the tests. I implemented this algorithm and used solidity-coverage results to localise bugs in Ethereum smart contracts. Let’s start at the beginning; the motivation for fault localisation. Imagine you’re just developing a new feature and you run your test suite.

Coming up with properties can be a difficult task! In this previous post we talked about starting to write Scribble properties. Here I’m going to explore four strategies to accelerate annotating your smart contracts! As you might already know, Scribble enables you to write properties that you can then test automatically using methods such as fuzzing and symbolic execution. Sounds awesome, doesn’t it? But how do you come up with those properties?

Writing smart contract properties - A new approach to testing Scribble allows you to write smart contract properties that can be automatically tested using fuzzing and symbolic execution techniques. Writing properties requires a bit of a mindset shift. This article will talk about that shift, to go from unit testing to property-based testing with Scribble. If you’re a developer then I’m sure you’re familiar with unit testing, an approach where you write small (unit) test cases to see if a component behaves as expected.

Making sure that smart contracts are secure and bug-free has never been more critical. Unfortunately, it remains a difficult task. While there are helpful tools for automatic testing and formal verification, ensuring the correctness of smart contracts continues to be a time-intensive and challenging task. To make things worse, each tool often has a steep learning curve, and it is often uncertain whether it’s even right for the job. That is why we’ve developed Scribble: a verification language and runtime verification tool.

A checklist for developers and security engineers to make use of when working with contracts that interact with many different tokens, especially if they want to support user-inputted tokens.

The second Solidity Underhanded Contest is here. This is your call to arms.

Announcing the first version of an RPC attack framework for blockchain nodes.

Mythril is an analysis tool which uses symbolic execution to find vulnerabilities in smart contracts. Mythril even generates exploits for the vulnerabilities that it finds 🚀. In a previous article, I wrote about Mythril internals and symbolic execution. In this article, I’ll show how I use Mythril to detect Ownership takeover vulnerabilities. I’ll also use Mythril’s new plugin system install and release plugins with ease! Introduction Out of the box, Mythril comes with several zero-setup detection modules.