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

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.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy