CyberCode Academy

Course 3 - Mastering Nuclei for Bug Bounty | Episode 8: Nuclei File-Based Templates: Implementing Content Matching and Secret Extraction

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In this lesson, you’ll learn about:
  • Nuclei file-based templates — purpose: extending Nuclei beyond HTTP to scan local files and codebases for sensitive content (hard‑coded secrets, API keys, credentials, tokens).
  • File block basics: replace requests with a file: block in the template to target files instead of sending network requests.
  • Targeting options:
    • extensions: specify file types to scan (e.g., txt, py).
    • - or hyphen all / match all patterns to search across all extensions.
    • max-size: limit (bytes) to skip very large files (e.g., 1024) and save resources.
    • no-recursive: disable recursive directory traversal when needed.
  • Matchers for file content:
    • Word matchers: find exact whole-word occurrences.
    • Regex matchers: use regexes for flexible/patterned matching (e.g., API key formats).
    • Combine part/context and status-like conditions to reduce false positives.
  • Extractors — pulling secrets:
    • Define extractors (word or regex) to capture the actual secret/token when a matcher hits.
    • Use extractors to output matched values (e.g., the API key string) for triage.
  • Practical workflow:
    • Build the file template with id/info/file/matchers/extractors.
    • Validate YAML (YAML Lint) and test locally on a safe directory.
    • Run Nuclei pointed at a path or file list and review extracted results.
  • Use cases: auditing repos for hard‑coded credentials, scanning downloaded code archives, searching config folders for secrets, or reviewing build artifacts before release.
  • Safety & operational tips:
    • Only scan files and code you’re authorized to analyze.
    • Set reasonable max-size and avoid scanning entire OS trees unnecessarily.
    • Use precise regexes to reduce false positives and noisy output.
    • Securely handle and store any extracted secrets (treat as sensitive data).
  • Core takeaway: Nuclei file templates are a powerful, scriptable way to automate discovery and extraction of sensitive content in local files — combine careful matcher design, extractors, and safety practices for effective, responsible audits.












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CyberCode AcademyBy CyberCode Academy