Buttercup is a Cyber Reasoning System (CRS) developed by Trail of Bits for the DARPA AIxCC (AI Cyber Challenge). Buttercup finds and patches software vulnerabilities in open-source code repositories like example-libpng. It starts by running an AI/ML-assisted fuzzing campaign (built on oss-fuzz) for the program. When vulnerabilities are found, Buttercup analyzes them and uses a multi-agent AI-driven patcher to repair the vulnerability. Buttercup system consists of several components:

• Orchestrator: Coordinates the overall task process and manages the workflow
• Seed Generator: Creates inputs for vulnerability discovery
• Fuzzer: Discovers vulnerabilities through intelligent fuzzing techniques
• Program Model: Analyzes code structure and semantics for better understanding
• Patcher: Generates and applies security patches to fix vulnerabilities

• CPU: 8 cores
• Memory: 16 GB RAM
• Storage: 100 GB available disk space
• Network: Stable internet connection for downloading dependencies

Note: Buttercup uses third-party AI providers (LLMs from companies like OpenAI, Anthropic and Google), which cost money. Please ensure that you manage per-deployment costs by using the built-in LLM budget setting.

Note: Buttercup works best with access to models from OpenAI and Anthropic, but can be run with at least one API key from one third-party provider (support for Gemini coming soon).

• linux x86_64 (fully supported)
• ARM64 (partial support for upstream Google OSS-Fuzz projects)

Before setup, ensure you have these packages installed:

# Ubuntu/Debian
sudo apt-get update
sudo apt-get install -y make curl git

# RHEL/CentOS/Fedora
sudo yum install -y make curl git
# or
sudo dnf install -y make curl git

# MacOS
brew install make curl git

Buttercup works with:

• C source code repositories that are OSS-Fuzz compatible
• Java source code repositories that are OSS-Fuzz compatible
• Projects that build successfully and have existing fuzzing harnesses

1. Clone the repository with submodules:

git clone --recurse-submodules https://github.com/trailofbits/buttercup.git
cd buttercup

2. Run automated setup (Recommended)

make setup-local

This script will install all dependencies, configure the environment, and guide you through the setup process.

Note: If you prefer manual setup, see the Manual Setup Guide.

3. Start Buttercup locally

make deploy-local

4. Verify local deployment:

make status

When a deployment is successful, you should see all pods in "Running" or "Completed" status.

5. Send Buttercup a simple task

Note: When tasked, Buttercup will start consuming third-party AI resources.

This command will make Buttercup pull down an example repo example-libpng with a known vulnerability. Buttercup will start fuzzing it to find and patch vulnerabilities.

make send-libpng-task

6. Access Buttercup's web-based GUI

Run:

make web-ui

Then navigate to http://localhost:31323 in your web browser.

In the GUI you can monitor active tasks and see when Buttercup finds bugs and generates patches for them.

7. Stop Buttercup

Note: This is an important step to ensure Buttercup shuts down and stops consuming third-party AI resources.

make undeploy

Buttercup includes local SigNoz deployment by default for comprehensive system observability. You can access logs, traces, and metrics through the SigNoz UI:

make signoz-ui

Then navigate to http://localhost:33301 in your web browser to view:

• Distributed traces
• Application metrics
• Error monitoring
• Performance insights

If you configured LangFuse during setup, you can also monitor LLM usage and costs there.

For additional log access methods, see the Quick Reference Guide.

• Quick Reference Guide - Common commands and troubleshooting
• Manual Setup Guide - Detailed manual installation steps
• AKS Deployment Guide - Production deployment on Azure
• Contributing Guidelines - Development workflow and standards
• Deployment Documentation - Advanced deployment configuration
• Writing Custom Challenges - Custom project configuration and setup