security-best-practices

name

security-best-practices

description

Perform language and framework specific security best-practice reviews and suggest improvements. Trigger only when the user explicitly requests security best practices guidance, a security review/report, or secure-by-default coding help. Trigger only for supported languages (python, javascript/typescript, go). Do not trigger for general code review, debugging, or non-security tasks. Do not use for security-hardening (OWASP Top 10 controls), security-threat-model (threat enumeration), or auth-patterns (auth implementation).

Purpose

Load language- and framework-specific secure-coding guidance from this skill's references/ directory, then apply it: write secure-by-default code, passively flag critical vulnerabilities, or produce a prioritized security report with fixes.

Operating procedure

1. Identify languages and frameworks

• Determine ALL primary languages and frameworks in scope (frontend + backend).
• Inspect the repo if unclear; list evidence for your determination.

2. Load reference guidance

• Check references/ for files matching <language>-<framework>-<stack>-security.md.
• Also check <language>-general-<stack>-security.md for framework-agnostic guidance.
• For web apps with unspecified frontend framework, load javascript-general-web-frontend-security.md.
• Read ALL matching reference files for the identified stack.

3. Choose operating mode

Mode A — Secure-by-default coding: Use loaded guidance to write new code securely. No report needed.

Mode B — Passive detection: While working on other tasks, flag critical vulnerabilities and major deviations from guidance. Focus on highest-impact issues only.

Mode C — Full security report: When user explicitly requests a review. Produce security_best_practices_report.md (or user-specified path). See Output defaults below.

4. Decision tree

• Language/framework unclear → inspect repo, list evidence.
• Matching guidance in references/ → load and follow.
• No matching guidance → use well-known best practices; if generating a report, disclose that concrete guidance is unavailable.

5. Apply fixes

• Fix one finding at a time with concise comments explaining the security rationale.
• Check for regressions — insecure code is often load-bearing. Prefer well-informed fixes over quick patches.
• Follow the project's commit and testing workflow. Use clear commit messages referencing the best practice.
• Consider second-order impacts and inform the user before making changes.

Overrides

Project documentation or prompt files may override specific best practices. When overriding:

• Comply without arguing, but MAY report the override.
• Suggest documenting the override and rationale in the project for future reference.

General security advice (language-agnostic)

Public resource IDs: Use UUID4 or random hex instead of auto-incrementing integers to prevent enumeration.

TLS / secure cookies: Do not flag missing TLS as a vulnerability in dev environments. Only set Secure cookie flag when TLS is confirmed. Provide an env flag to toggle. Avoid recommending HSTS — it has lasting side-effects (outages, user lockout) and is inappropriate for most codex-scoped projects.

Output defaults

Report written to security_best_practices_report.md (or user-specified path):

## Executive Summary
[1–2 sentence overview of findings]

## Critical Findings
| ID | Location (file:line) | Issue | Impact | Severity |
|----|---------------------|-------|--------|----------|
| 1  | auth.py:45          | ...   | ...    | Critical |

## High / Medium / Low Findings
[Same table format, grouped by severity]

## Recommended Fix Order
[Prioritized list with rationale]

After writing, summarize findings to user and state report path.

References

• https://owasp.org/www-project-application-security-verification-standard/
• https://cheatsheetseries.owasp.org/
• Language/framework guidance: references/<language>-<framework>-<stack>-security.md

Failure handling

• No reference guidance available: Use general best practices; disclose gap to user. Still flag critical vulnerabilities with high confidence.
• Language/framework not identifiable: Ask user to clarify or inspect package manifests, CI config, and file extensions for evidence.
• Report too large: Focus on critical and high severity findings first. Offer to expand to medium/low in a follow-up.
• Fixes cause regressions: Roll back, document the issue, and discuss with user before retrying. Do not force security fixes that break functionality.
• User overrides a best practice: Comply, document the override, and move on.