attack-tree.md

Attack Tree Analysis for sveltejs/svelte

Objective: Execute Arbitrary JavaScript in the context of a legitimate user's session.

Attack Tree Visualization

Execute Arbitrary JavaScript (Attacker's Goal)
├── Exploit Svelte-Specific Features/Misconfigurations
│   ├── 2. Misuse Context API
│   │   └── 2a. Unvalidated Context Data (L: H, I: H, E: M, S: M, D: M)
│   └── 3. Inject into {@html}
│       └── 3a. Unsanitized Input to {@html} (L: H, I: H, E: L, S: M, D: L)
└── Exploit Vulnerabilities in Svelte Compiler/Runtime
    └── 5. Exploit Runtime Issues
        └── 5a. Event Handler Manipulation (L: M, I: H, E: M, S: M, D: M)

Attack Tree Path: 2. Misuse Context API

• 2a. Unvalidated Context Data (Likelihood: High, Impact: High, Effort: Medium, Skill: Medium, Detection Difficulty: Medium)

  • Description: Svelte's context API allows components to share data without prop drilling. If a component uses data from the context without validating it, an attacker can inject malicious code. This is particularly dangerous if the context is populated from user input, external APIs, or other untrusted sources.
  • Attack Scenario:
    1. The attacker finds a way to influence the data that is placed into the context. This could be through a separate vulnerability (e.g., a form that doesn't properly sanitize input), or by manipulating a legitimate user into performing an action that modifies the context (e.g., clicking a malicious link).
    2. The attacker injects malicious JavaScript code into the context data.
    3. A component reads the malicious data from the context and uses it without validation, for example, by directly inserting it into the DOM using innerHTML or by using it in a template expression that is evaluated.
    4. The injected JavaScript code executes in the context of the victim's browser.
  • Mitigation Strategies:
    • Strict Input Validation: Always validate and sanitize any data that is placed into the context, regardless of its source. Use a whitelist approach, allowing only known-good values.
    • Type Checking: Use TypeScript or similar type-checking mechanisms to ensure that the context data conforms to the expected type and structure.
    • Context Isolation: Limit the scope of the context to only the components that absolutely need access to it. Avoid using a single, global context for all application data.
    • Consider Alternatives: If possible, consider alternatives to the context API for sharing data, such as props or a dedicated state management library. These alternatives may offer better control and security.

Attack Tree Path: 3. Inject into {@html}

• 3a. Unsanitized Input to {@html} (Likelihood: High, Impact: High, Effort: Low, Skill: Medium, Detection Difficulty: Low)

  • Description: The {@html} tag in Svelte is designed to render raw HTML. If an attacker can control the content passed to {@html}, they can inject arbitrary HTML, including <script> tags containing malicious JavaScript. This is a classic Cross-Site Scripting (XSS) vulnerability.
  • Attack Scenario:
    1. An application uses {@html} to display user-provided content, such as comments, forum posts, or profile information.
    2. An attacker submits content containing malicious JavaScript code, often disguised within seemingly harmless HTML tags or attributes (e.g., <img src=x onerror=alert(1)>).
    3. The application renders the attacker's content using {@html} without sanitization.
    4. The injected JavaScript code executes in the context of the victim's browser.
  • Mitigation Strategies:
    • Avoid {@html} whenever possible: This is the most effective mitigation. Use Svelte's built-in templating features to render dynamic content whenever possible.
    • Use a Robust HTML Sanitizer: If you must use {@html}, use a well-vetted and actively maintained HTML sanitization library like DOMPurify. Configure the sanitizer to allow only a very restricted set of HTML tags and attributes.
    • Content Security Policy (CSP): Implement a strict CSP to limit the sources from which scripts can be executed. This can help mitigate the impact of XSS even if a vulnerability exists.
    • Input Validation: While sanitization is the primary defense, also validate user input to ensure it conforms to expected formats and lengths.

Attack Tree Path: 5. Exploit Runtime Issues

• 5a. Event Handler Manipulation (Likelihood: Medium, Impact: High, Effort: Medium, Skill: Medium, Detection Difficulty: Medium)

  *   **Description:** Svelte compiles event handlers into efficient JavaScript code. If an attacker can manipulate the data used to construct these event handlers, they might be able to inject malicious code. This is less direct than `{@html}` injection but can still lead to XSS.
  *   **Attack Scenario:**
      1.  An application dynamically creates event handlers based on user input or data from an external source. For example, it might use a string from a database to determine the function to be called when a button is clicked.
      2.  An attacker crafts malicious input that, when used to construct the event handler, results in the execution of arbitrary JavaScript. This might involve using string concatenation or template literals in an insecure way.
      3.  When the user interacts with the element (e.g., clicks the button), the attacker's code is executed.
  *   **Mitigation Strategies:**
      *   **Avoid Dynamic Event Handler Creation:** If possible, define event handlers statically in your Svelte components.
      *   **Use Indirect References:** If you must create event handlers dynamically, use a lookup table or a similar mechanism to map user input to predefined functions, rather than directly constructing the handler code from user input.
      *   **Input Validation and Sanitization:** As with other attack vectors, validate and sanitize any data that is used to construct event handlers.
      *   **Code Reviews:** Carefully review any code that deals with dynamic event handling to ensure that it is not vulnerable to injection attacks.