Log Parser

A TypeScript utility for parsing Medusa, Echidna, and Halmos fuzzing / symbolic execution logs.

Web

Used in:

• Recon VSCode Extension
• https://getrecon.xyz/tools/medusa
• https://getrecon.xyz/tools/echidna
• https://getrecon.xyz/tools/halmos

NPM

https://www.npmjs.com/package/@recon-fuzz/log-parser

Installation

yarn add @recon-fuzz/log-parser

Usage

import{processLogs,Fuzzer}from'@recon-fuzz/log-parser';// Process Medusa logsconstmedusaResults=processLogs(medusaLogContent,Fuzzer.MEDUSA);// Process Echidna logsconstechidnaResults=processLogs(echidnaLogContent,Fuzzer.ECHIDNA);// Process Halmos logsconsthalmosResults=processLogs(halmosLogContent,Fuzzer.HALMOS);

API Reference

processLogs(logs: string, tool: Fuzzer): FuzzingResults

Processes fuzzing logs and returns structured results.

Parameters

• logs: string - The raw log content as a string
• tool: Fuzzer - The tool used (Fuzzer.MEDUSA | Fuzzer.ECHIDNA | Fuzzer.HALMOS)

Returns: FuzzingResults

interfaceFuzzingResults{duration: string;coverage: number;failed: number;passed: number;results: any[];traces: any[];brokenProperties: any[];numberOfTests: number;}

Converting Logs to Foundry Tests

Medusa, Echidna and Halmos logs can be converted into Foundry test cases using the provided utility functions.

Medusa & Echidna

// Echidna -> Foundry test functionsimport{echidnaLogsToFunctions}from'@recon-fuzz/log-parser';constechidnaFoundryTests=echidnaLogsToFunctions(echidnaLogs,"test_identifier","brokenProperty",// the property name that failed{roll: true,time: true,prank: true}// vm helpers configuration);// Medusa -> Foundry test functionsimport{medusaLogsToFunctions}from'@recon-fuzz/log-parser';constmedusaFoundryTests=medusaLogsToFunctions(medusaLogs,"test_identifier",{roll: true,time: true,prank: true});

Halmos

Halmos produces counterexamples consisting of parameter assignments and a symbolic execution call sequence. These can be transformed into Foundry tests.

import{halmosLogsToFunctions}from'@recon-fuzz/log-parser';// Convert all broken properties (if any) to test functionsconsthalmosFoundryTests=halmosLogsToFunctions(halmosLogs,"test_identifier");

The conversion handles:

• VM state manipulation (block numbers, timestamps)
• Actor simulation (pranks for different senders)
• Function call sequences / symbolic traces
• Parameter reconstruction for Halmos counterexamples
• Special data types (addresses, bytes)

Generated tests include the exact sequence of calls that triggered the property violation, making it easy to reproduce and debug issues found during fuzzing or symbolic exploration.

Development

Requirements

• Node.js (>= 14.x)
• yarn or npm

Setup

1. Clone the repository
2. Install dependencies:

yarn install

Scripts

• yarn build - Build the package
• yarn test - Run tests
• yarn lint - Run linting

License

https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt