mitigations.md

Mitigation Strategies Analysis for norman/friendly_id

Mitigation Strategy: Enforce Uniqueness within friendly_id Configuration

Description: This strategy leverages friendly_id's built-in features to manage slug uniqueness, including scopes and conflict resolution.

1. Application-Level Validation (using friendly_id):
   • Step 1 (Developer): In your ActiveRecord model, use the validates clause in conjunction with friendly_id.

     class YourModel < ApplicationRecord
       extend FriendlyId
       friendly_id :name, use: :slugged # Or your configuration
     
       validates :slug, presence: true, uniqueness: { scope: :your_scope, case_sensitive: false }
     end

   • Step 2 (Developer): If you have a custom scope, replace :your_scope with the actual scope (e.g., :user_id, [:category_id, :year]). If you don't have a scope, remove the scope option. This is crucial for preventing collisions within the intended scope.
   • Step 3 (Developer): Ensure case_sensitive: false is set unless you specifically need case-sensitive slugs (which is rare and generally discouraged).
2. Handle Uniqueness Failures Gracefully (within friendly_id):
   • Step 1 (Developer): Understand friendly_id's default conflict resolution behavior. It typically appends a sequence number or UUID to make the slug unique. Read the friendly_id documentation on conflict resolution.
   • Step 2 (Developer): If you need custom retry logic, override the should_generate_new_friendly_id? method in your model. This allows you to control when a new slug is generated.

     def should_generate_new_friendly_id?
       name_changed? || super # Regenerate if name changes, or if friendly_id decides it's needed
     end

   • Step 3 (Developer): You can also customize the normalize_friendly_id method to control how the slug is generated, including how conflicts are resolved. This is more advanced and rarely needed.

• Threats Mitigated:

  • Slug Uniqueness Violations (within friendly_id's scope): (Severity: High) - Prevents data corruption, incorrect record retrieval, and application errors caused by duplicate slugs within the defined scope.
  • Incorrect Record Retrieval (within scope): (Severity: High) - Ensures that users are directed to the correct record when using a slug, considering the defined scope.

• Impact:

  • Slug Uniqueness Violations (within scope): Risk significantly reduced (effectiveness depends on correct scope definition).
  • Incorrect Record Retrieval (within scope): Risk significantly reduced.

• Currently Implemented:

  • Application-Level Validation: Yes, in app/models/post.rb
  • Handle Uniqueness Failures Gracefully: Partially, relying on friendly_id's default behavior.

• Missing Implementation:

  • Custom retry logic (overriding should_generate_new_friendly_id?) is missing. We should evaluate if the default behavior is sufficient.

Mitigation Strategy: Strengthen Slug Generation with friendly_id

Description: This strategy uses friendly_id's features to create less predictable slugs, making them harder to guess.

1. Use SecureRandom (within slug_candidates):
   • Step 1 (Developer): Modify your slug_candidates method in your model to include a SecureRandom component. This is essential if your slug isn't solely based on a user-provided, unpredictable attribute.

     # app/models/your_model.rb
     friendly_id :slug_candidates, use: :slugged
     
     def slug_candidates
       [
         :name,
         [:name, SecureRandom.hex(8)],  # Append 8 random hex characters
         [:name, SecureRandom.uuid]     # Or, append a UUID
       ]
     end

   • Step 2 (Developer): Choose an appropriate level of randomness (e.g., hex(8), uuid). Longer is generally better for security. This makes the slug less predictable even if the name is guessable.
2. Avoid Predictable Patterns (in slug_candidates):
   • Step 1 (Developer): Never use sequential IDs or timestamps alone as the sole basis for slugs within the slug_candidates array.
   • Step 2 (Developer): If using timestamps, always combine them with a random component (e.g., SecureRandom.hex) within the slug_candidates array.

• Threats Mitigated:

  • Slug Generation Predictability: (Severity: Medium) - Makes it harder for attackers to guess valid slugs.
  • Resource Enumeration: (Severity: Medium) - Prevents attackers from systematically trying different slugs to discover all resources.

• Impact:

  • Slug Generation Predictability: Risk significantly reduced.
  • Resource Enumeration: Risk significantly reduced.

• Currently Implemented:

  • Using slug_candidates with :name in app/models/post.rb. This is partially implemented.

• Missing Implementation:

  • We are not currently appending a SecureRandom component to the slug_candidates. This is a critical missing piece and should be implemented immediately. We need to modify the slug_candidates method in app/models/post.rb.

Mitigation Strategy: Utilize friendly_id's History Module

Description: This strategy uses friendly_id's :history module to handle slug changes gracefully and prevent broken links.

1. Enable the History Module:
   • Step 1 (Developer): Include the :history module in your friendly_id configuration.

     # app/models/your_model.rb
     friendly_id :name, use: [:slugged, :history]

   • Step 2 (Developer): Run the friendly_id generator to create the necessary migration: rails generate friendly_id
   • Step 3 (Developer): Run the migration: rails db:migrate
2. Understand Redirect Behavior:
   • Step 1 (Developer): friendly_id will automatically create records in the friendly_id_slugs table when a slug changes.
   • Step 2 (Developer): When you use YourModel.friendly.find(old_slug), friendly_id will automatically find the correct record, even if the slug has changed. It handles the redirection internally.

• Threats Mitigated:

  • Broken Links After Slug Changes: (Severity: Medium) - Prevents broken links if a slug is updated.
  • SEO Issues After Slug Changes: (Severity: Medium) - Maintains SEO by allowing search engines to find the content even after a slug change.

• Impact:

  • Broken Links: Risk significantly reduced.
  • SEO Issues: Risk significantly reduced.

• Currently Implemented:

  • We are using the :history module in app/models/post.rb. The migration has been run.

• Missing Implementation:

  • None. This strategy is fully implemented.

Mitigation Strategy: Customize Slug Generation with normalize_friendly_id (Advanced)

Description: This strategy involves overriding the normalize_friendly_id method to have fine-grained control over how slugs are generated, including sanitization and conflict resolution. This is generally not needed if you're using slug_candidates and basic sanitization appropriately.

1. Override normalize_friendly_id:
   • Step 1 (Developer): Define the normalize_friendly_id method in your model.

     # app/models/your_model.rb
     def normalize_friendly_id(input)
       # Custom sanitization and normalization logic here
       # Example:
       input.to_s.downcase.gsub(/[^a-z0-9\-_]+/, '-')
     end

   • Step 2 (Developer): Implement your custom logic. This could include:
     • More aggressive sanitization.
     • Custom character replacements.
     • Alternative conflict resolution strategies (though slug_candidates is usually preferred).
2. Thorough Testing:
   • Step 1 (Developer): Test extensively to ensure your custom logic works as expected and doesn't introduce any regressions.

• Threats Mitigated:

  • Slug Manipulation/Injection (Fine-grained Control): (Severity: High) - Allows for very specific sanitization rules.
  • Slug Uniqueness Violations (Custom Conflict Resolution): (Severity: High) - Provides an alternative way to handle conflicts (but slug_candidates is generally better).

• Impact:

  • Slug Manipulation/Injection: Risk can be further reduced (but proper sanitization before calling friendly_id is still crucial).
  • Slug Uniqueness Violations: Risk can be managed differently (but slug_candidates and database constraints are the primary defenses).

• Currently Implemented:

  • Not implemented. We are relying on friendly_id's default normalization.

• Missing Implementation:

  • Not currently needed, as we should focus on proper sanitization before passing data to friendly_id. This is an advanced technique to be used only if absolutely necessary.