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Threat Model Analysis for ryanb/cancan

Threat: Overly Permissive can Definitions

  • Threat: Overly Permissive can Definitions

    • Description: An attacker exploits overly broad can rules in the Ability class. For example, a rule like can :manage, :all grants excessive privileges. The attacker, even with a low-privilege account, attempts actions they shouldn't be able to perform, such as deleting other users' data or accessing administrative features. They might try different URLs, manipulate form data, or use API calls to test these boundaries.
    • Impact: Unauthorized data access, modification, or deletion. Compromise of sensitive data. Elevation of privilege. Potential for complete system compromise.
    • Affected CanCan Component: Ability class, can method.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Principle of Least Privilege: Define the most restrictive can rules possible. Grant only the absolute minimum permissions required for each user role.
      • Use Specific Actions: Instead of can :manage, use specific actions like can :create, can :read, can :update, can :destroy.
      • Use Conditions: Employ conditional abilities extensively (e.g., can :update, Article, user_id: user.id).
      • Avoid manage :all: This should be avoided unless absolutely necessary and thoroughly justified.
      • Regular Audits: Periodically review and refine the Ability class to ensure permissions remain appropriate.

Threat: Logic Errors in Ability Class

  • Threat: Logic Errors in Ability Class

    • Description: An attacker leverages flaws in the conditional logic within the Ability class. This could be due to incorrect Ruby code, misunderstandings of boolean operators, or complex conditions that are not properly handled. The attacker might try to exploit edge cases or unexpected combinations of conditions to gain unauthorized access.
    • Impact: Unintended access to resources or actions. Denial of service for legitimate users if authorization checks incorrectly deny access.
    • Affected CanCan Component: Ability class, conditional logic within can definitions.
    • Risk Severity: High
    • Mitigation Strategies:
      • Simplify Logic: Keep the logic within the Ability class as simple and readable as possible.
      • Unit Testing: Thoroughly unit test the Ability class, covering all possible conditions and combinations.
      • Helper Methods: Extract complex logic into well-named helper methods to improve readability and testability.
      • Code Reviews: Mandatory code reviews with a focus on the correctness of the authorization logic.

Threat: Missing Authorization Checks (load_and_authorize_resource or authorize!)

  • Threat: Missing Authorization Checks (load_and_authorize_resource or authorize!)

    • Description: An attacker directly accesses a controller action or resource that lacks the necessary load_and_authorize_resource or authorize! call. They might discover this through code inspection (if available), brute-forcing URLs, or analyzing network traffic. This bypasses all CanCan(Can) authorization.
    • Impact: Complete bypass of authorization, allowing any user (even unauthenticated ones) to access the resource or perform the action. This is a critical vulnerability.
    • Affected CanCan Component: Controller actions, load_and_authorize_resource method, authorize! method.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Consistent Use: Enforce a strict policy of using load_and_authorize_resource in all relevant controllers.
      • Controller-Level Authorization: Prefer load_and_authorize_resource at the controller level to protect all actions by default.
      • Automated Checks: Use static analysis tools or linters to detect missing authorization checks.
      • Code Reviews: Thorough code reviews to ensure authorization checks are present in all necessary locations.

Threat: Incorrect accessible_by Implementation

  • Threat: Incorrect accessible_by Implementation

    • Description: An attacker exploits an incorrectly implemented accessible_by query. This could involve manipulating parameters to influence the query, causing it to return more records than intended (data leakage) or fewer records (denial of service). The attacker might try to inject SQL fragments or manipulate filter parameters.
    • Impact: Data leakage (exposure of sensitive information). Denial of service (legitimate users unable to access data).
    • Affected CanCan Component: accessible_by method.
    • Risk Severity: High
    • Mitigation Strategies:
      • Thorough Testing: Extensively test accessible_by queries with various inputs and edge cases.
      • Input Validation: Strictly validate and sanitize all user-supplied parameters used in accessible_by queries.
      • Parameterized Queries: Ensure that accessible_by is generating parameterized queries to prevent SQL injection vulnerabilities.
      • Understand Scope: Ensure developers have a clear understanding of how accessible_by interacts with database scopes.

Threat: Insecure Direct Object References (IDOR) with accessible_by (Indirect)

  • Threat: Insecure Direct Object References (IDOR) with accessible_by (Indirect)

    • Description: While CanCanCan itself helps prevent IDOR, if accessible_by is not used correctly, or if a user can manipulate parameters to influence the query generated by accessible_by, they might be able to access records they shouldn't. The attacker changes ID parameter in request to access other users data.
    • Impact: Unauthorized data access.
    • Affected CanCan Component: accessible_by method.
    • Risk Severity: High
    • Mitigation Strategies:
      • Careful Parameter Handling: Ensure that user-supplied parameters cannot be used to manipulate the accessible_by query in unintended ways.
      • Input Validation: Validate all user input to prevent unexpected values from being passed to accessible_by.
      • Use with current_ability: Ensure that accessible_by is always used in conjunction with current_ability to correctly scope the query to the current user's permissions.