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Threat Model Analysis for quick/nimble

Threat: Route Hijacking via Regex Injection

  • 1. Threat: Route Hijacking via Regex Injection

    • Description: An attacker crafts malicious input to manipulate regular expressions used in Nimble's route definitions. If user input is (incorrectly) used to build routes, the attacker can inject regex metacharacters (e.g., .*, .+) to alter route matching, directing requests to unintended handlers.
    • Impact: Bypass of authentication/authorization, access to internal APIs/admin functions, denial of service (by routing to resource-intensive handlers).
    • Affected Nimble Component: router module; functions defining routes (e.g., get, post, addRoute) that accept regular expressions.
    • Risk Severity: High (if user input influences route definitions; could be lower if routes are static but very complex).
    • Mitigation Strategies:
      • Avoid Dynamic Routes: Do not construct routes from user input. Use static definitions.
      • Strict Input Validation: If dynamic routes are unavoidable, rigorously validate and sanitize any user input used in route construction. Use a whitelist.
      • Escape Regex Metacharacters: If user input must be in a regex, properly escape all metacharacters using Nim's escaping functions or a dedicated library.
      • Least Privilege: Handlers should have minimal privileges. Limit the impact even if a route is hijacked.
      • Regex Complexity Limits: Limit regex complexity to prevent ReDoS (Regular Expression Denial of Service).

Threat: Middleware Bypass via Ordering Error

  • 2. Threat: Middleware Bypass via Ordering Error

    • Description: An attacker exploits incorrect middleware ordering. If authentication middleware is placed after a middleware performing sensitive operations, the attacker bypasses authentication by triggering the sensitive operation before checks.
    • Impact: Unauthorized access to protected resources, data breaches, privilege escalation.
    • Affected Nimble Component: router module and the mechanism for defining/applying middleware (e.g., use function). The middleware functions themselves are relevant.
    • Risk Severity: High
    • Mitigation Strategies:
      • Careful Middleware Ordering: Explicitly define middleware execution order. Place security-critical middleware (authentication, authorization) before sensitive operations.
      • Centralized Configuration: Manage middleware in a single, well-defined location.
      • Testing: Thoroughly test middleware ordering (positive and negative cases). Try to bypass security.
      • "Fail-Safe" Middleware: Consider a "fail-safe" middleware at the beginning that denies access unless explicitly granted by later authentication/authorization.

Threat: Server-Side Template Injection (SSTI) via Unescaped User Input

  • 3. Threat: Server-Side Template Injection (SSTI) via Unescaped User Input

    • Description: An attacker provides input embedded directly into a Nimble template without escaping. If the templating engine (Nimble's or a third-party) is vulnerable or allows code execution, the attacker injects malicious code that runs on the server. This is very dangerous if the engine allows access to Nim's standard library or system functions.
    • Impact: Remote Code Execution (RCE), complete server compromise, data exfiltration.
    • Affected Nimble Component: The templating engine used with Nimble (Nim's built-in features or a library like nim-templates). Functions rendering templates and inserting data (e.g., render).
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Automatic Escaping: Use a templating engine with automatic contextual escaping (escaping based on context – HTML, JS, etc.). Verify it's enabled and working.
      • Manual Escaping: If automatic escaping is unavailable/unreliable, always manually escape user data before template insertion. Use the correct function (e.g., escapeHtml, escapeJs).
      • Input Validation: Validate and sanitize all user input before it's used in a template. This is an extra defense layer.
      • Template Sandboxing: If possible, use a templating engine with sandboxing, limiting code execution capabilities within templates.
      • Content Security Policy (CSP): Implement a strict CSP to mitigate SSTI impact by limiting executable code types.