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Mitigation Strategies Analysis for chartjs/chart.js

Mitigation Strategy: Data Sanitization and Validation (Enhanced for Chart.js)

Description:

  1. Identify Chart.js Data Points: Determine all data points passed directly to Chart.js (labels, datasets, values, colors, options that accept data, etc.).
  2. Define Data Types: For each Chart.js data point, define the expected data type (number, string, boolean, etc., as per Chart.js documentation).
  3. Implement Type Checking:
    • Before Chart.js Interaction: Immediately before passing data to Chart.js functions (e.g., new Chart(), chart.update()), use JavaScript's typeof or TypeScript to ensure data matches the expected types. Reject or sanitize.
  4. Whitelist Characters (for Strings in Chart.js):
    • For string data passed to Chart.js (labels, tooltips, etc.), create a whitelist of allowed characters.
    • Implement a function that checks if a string contains only whitelisted characters before passing it to Chart.js.
  5. Use a Sanitization Library (for Chart.js Data):
    • Use a library like DOMPurify.
    • Call DOMPurify.sanitize() on all user-provided data immediately before it's used in Chart.js. This is the most critical step for preventing XSS through Chart.js.
  6. Context-Specific Encoding (Chart.js Contexts): If data is used in specific Chart.js contexts (e.g., tooltips, custom HTML labels), ensure it's encoded appropriately for that specific Chart.js feature. Basic HTML encoding might not be sufficient if Chart.js further processes the data. Consult Chart.js documentation for the specific context.
  7. Regular Expression Validation (Chart.js Input): If using regular expressions, ensure they are strict, tested, and used in conjunction with other validation methods, specifically targeting the data passed to Chart.js.

Threats Mitigated:

  • Cross-Site Scripting (XSS) via Chart.js: (Severity: High) - Prevents injection of malicious JavaScript into chart data rendered by Chart.js.
  • Chart.js Data Corruption: (Severity: Medium) - Prevents invalid data from causing errors or unexpected behavior within Chart.js.
  • Indirect Code Injection (through Chart.js): (Severity: High) - Reduces the risk of code injection through Chart.js plugins or custom code that interacts with unsanitized Chart.js data.

Impact:

  • XSS: Risk significantly reduced (near elimination with correct implementation).
  • Chart.js Data Corruption: Risk significantly reduced.
  • Indirect Code Injection: Risk significantly reduced.

Currently Implemented:

  • Describe where this is implemented, specifically focusing on code that directly interacts with Chart.js (e.g., "Implemented in the renderChart() function before calling new Chart(). Uses DOMPurify and type checking for all data passed to Chart.js.").

Missing Implementation:

  • Describe where this is missing, again focusing on direct Chart.js interactions (e.g., "Missing character whitelisting for labels passed to Chart.js. Missing context-specific encoding for tooltip data.").

Mitigation Strategy: Chart Configuration Option Whitelisting (Direct Chart.js Control)

Description:

  1. Identify User-Controllable Chart.js Options: List all Chart.js configuration options that users can directly or indirectly influence (e.g., through form inputs, URL parameters).
  2. Create a Chart.js Option Whitelist: Define a whitelist of allowed Chart.js options and their allowed values. This should be as restrictive as possible, based on the required Chart.js functionality. Use the example structure from the previous response, but ensure it's tailored to your application's needs.
  3. Implement Validation (Before Chart.js Initialization/Update):
    • Before new Chart() or chart.update(): Immediately before initializing or updating a Chart.js instance, validate any user-influenced configuration options against the whitelist.
    • Reject Invalid Options/Values: If an option or value is not in the whitelist, reject it or use a safe default value. Do not pass it to Chart.js.
  4. Server-Side Chart.js Configuration (as Default): Define default Chart.js configurations on the server. Only allow the client to override specific, whitelisted options, and validate those overrides before passing them to Chart.js.

Threats Mitigated:

  • XSS via Chart.js Configuration: (Severity: High) - Prevents attackers from manipulating Chart.js options to inject malicious code (e.g., through custom plugins or event handlers that are part of the Chart.js configuration).
  • DoS via Chart.js Configuration: (Severity: Medium) - Prevents setting Chart.js options that could lead to excessive resource consumption (e.g., overly complex animations, configurations that trigger excessive rendering).
  • Unexpected Chart.js Behavior: (Severity: Low) - Prevents users from setting configurations that break the chart or lead to unexpected Chart.js rendering.

Impact:

  • XSS: Risk significantly reduced.
  • DoS: Risk significantly reduced.
  • Unexpected Behavior: Risk significantly reduced.

Currently Implemented:

  • Describe where this is implemented, focusing on code that directly sets Chart.js options (e.g., "Implemented in the createChartConfig() function, which is called before new Chart(). Uses a whitelist defined in chartConfigWhitelist.js.").

Missing Implementation:

  • Describe where this is missing (e.g., "Missing validation for options passed to chart.update(). Currently, only the initial configuration is validated.").

Mitigation Strategy: Plugin Management (Direct Chart.js Plugin Interaction)

Description:

  1. Inventory Chart.js Plugins: Create a list of all Chart.js plugins used in the project.
  2. Vetting Process (for new Chart.js plugins):
    • Necessity: Determine if the plugin is truly necessary for Chart.js functionality.
    • Source Code Review (Focus on Chart.js Interaction): Examine how the plugin interacts with Chart.js. Look for:
      • How it handles data passed to it.
      • Whether it uses eval() or similar functions in its interaction with Chart.js.
      • Whether it modifies Chart.js's default behavior in potentially unsafe ways.
    • Maintainer Reputation: Research the plugin's maintainer.
    • Security History: Search for known vulnerabilities.
  3. Update Process (Chart.js Plugins):
    • Automated Checks: Use tools to check for updates and vulnerabilities in Chart.js plugins.
    • Prompt Updates: Apply security updates for Chart.js plugins promptly.
  4. Review Plugin's Interaction with Chart.js:
    • Examine how data is passed between your application and the plugin, and then to Chart.js.
    • Ensure that the plugin itself is following the same data sanitization and validation principles before interacting with Chart.js.

Threats Mitigated:

  • XSS via Chart.js Plugins: (Severity: High) - Vulnerabilities in plugins can be exploited to inject malicious code through Chart.js.
  • Other Plugin-Specific Vulnerabilities (affecting Chart.js): (Severity: Variable) - Plugins can introduce vulnerabilities that affect Chart.js's rendering or behavior.
  • Supply Chain Attacks (targeting Chart.js plugins): (Severity: High)

Impact:

  • XSS: Risk reduced.
  • Other Plugin-Specific Vulnerabilities: Risk reduced.
  • Supply Chain Attacks: Risk reduced.

Currently Implemented:

  • Describe the current process, specifically mentioning Chart.js plugins (e.g., "We use npm audit to check for vulnerabilities in Chart.js plugins. Plugins are manually reviewed before initial use, focusing on their interaction with Chart.js data and options.").

Missing Implementation:

  • Describe gaps (e.g., "No formal process for reviewing how plugins interact with Chart.js. Updates are not always applied promptly.").