Rails Security Review

Use this skill when the task is to review or harden Rails code from a security perspective.

Core principle: Prioritize exploitable issues over style. Assume any untrusted input can be abused.

Quick Reference

Review Order

1. Check authentication and authorization boundaries.
2. Check parameter handling and sensitive attribute assignment.
3. Check redirects, rendering, and output encoding.
4. Check file handling, network calls, and background job inputs.
5. Check secrets, logging, and operational exposure.
6. Verify each finding: Confirm it is exploitable with a concrete attack scenario before reporting. Exclude false positives (e.g., html_safe on a developer-defined constant, not user input).

Severity Levels

High

• Missing or bypassable authorization checks
• SQL, shell, YAML, or constantization injection paths
• Unsafe redirects or SSRF-capable outbound requests
• File upload handling that trusts filename, content type, or destination blindly
• Secrets or tokens stored in code, logs, or unsafe config

Medium

• Unscoped mass assignment through weak parameter filtering
• User-controlled HTML rendered without clear sanitization
• Sensitive data logged in plaintext
• Security-relevant behavior hidden in callbacks or background jobs without guardrails
• Brittle custom auth logic where framework primitives would be safer

Review Checklist

• Are permissions enforced on every sensitive action?
• Are untrusted inputs validated before database, filesystem, or network use?
• Are redirects and URLs constrained?
• Are secrets stored and logged safely?
• Are security assumptions explicit and testable?

Examples

High-severity (unscoped redirect):

# Bad: user-controlled redirect — open redirect / phishing risk
redirect_to params[:return_to]

# Good: relative path only
redirect_to root_path
# Good: allowlist
SAFE_PATHS = %w[/dashboard /settings].freeze
redirect_to(SAFE_PATHS.include?(params[:return_to]) ? params[:return_to] : root_path)

Medium-severity (mass assignment):

# Bad: privilege escalation risk
params.require(:user).permit!

# Good: explicit whitelist — never include role, admin, or privilege fields
params.require(:user).permit(:name, :email)

Pitfalls

See PITFALLS.md for the full list. Critical anti-patterns: permit! on any parameter set, html_safe on user content, SQL string interpolation, secrets in committed files.

Output Style

Write findings first. Order findings by review area — auth/authz always first:

1. Authentication and authorization findings
2. SQL/injection and parameter findings
3. Secrets, logging, and output findings

Do not reorder based on which issue looks most obvious. Even if SQL injection is more apparent, authorization findings lead the report.

For each finding include:

• Severity: label it High or Medium (not "High-Severity" or "Critical")
• Attack path or failure mode
• Affected file (name the specific file, e.g. app/controllers/documents_controller.rb)
• Smallest credible mitigation

Integration