deobfuscating-javascript-malware

Installation
SKILL.md

Deobfuscating JavaScript Malware

When to Use

  • Investigating a phishing page with obfuscated JavaScript that performs credential harvesting or redirect
  • Analyzing a web skimmer (Magecart-style) injected into an e-commerce site
  • Deobfuscating a JavaScript dropper that downloads and executes second-stage malware
  • Examining malicious email attachments containing HTML files with embedded obfuscated scripts
  • Analyzing browser exploit kits that use heavy JavaScript obfuscation to hide exploit delivery

Do not use for obfuscated JavaScript that is merely minified production code; use a standard beautifier instead.

Prerequisites

  • Node.js 18+ installed for executing and debugging JavaScript in a controlled environment
  • Python 3.8+ with jsbeautifier library for code formatting
  • Browser developer tools (Chrome DevTools) for controlled execution in an isolated browser
  • CyberChef (https://gchq.github.io/CyberChef/) for encoding/decoding operations
  • de4js or JStillery for automated JavaScript deobfuscation
Related skills
Installs
48
GitHub Stars
6.2K
First Seen
Mar 14, 2026