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Mitigation Strategies Analysis for ampproject/amphtml

Mitigation Strategy: Strict AMP Component Auditing and Management

  • Description:

    1. Inventory: Create a comprehensive list of all AMP components used in the project, including their versions and source (official AMP, third-party). This is AMP-specific because it deals with the amp-* components.
    2. Source Code Review: For each AMP component:
      • Obtain the source code.
      • Examine the code for potential vulnerabilities, focusing on how the component handles user input, generates output, and interacts with other AMP components or external resources. This is AMP-specific because the vulnerabilities are within the AMP component's logic.
      • Document any identified vulnerabilities.
    3. Update Mechanism: Establish a process for automatically updating all AMP components to their latest versions. This is crucial because AMP components are frequently updated with security patches.
    4. Least Privilege (AMP-Specific): Configure each AMP component with the minimum necessary attributes and data access. For example, restrict amp-list to only fetch data from specific, trusted endpoints. This leverages AMP's built-in restrictions.
    5. CVE Monitoring (AMP-Specific): Actively monitor for CVEs specifically related to the used AMP components.

  • Threats Mitigated:

    • XSS via AMP Components (High Severity): Directly addresses vulnerabilities within AMP components that could lead to XSS.
    • Data Exfiltration via AMP Components (Medium to High Severity): Limits the potential for compromised AMP components to leak data.
    • Component-Specific Vulnerabilities (Variable Severity): Addresses any other vulnerabilities specific to individual AMP components.

  • Impact:

    • XSS: Significantly reduces the risk (e.g., by 70-90%) if implemented thoroughly.
    • Data Exfiltration: Moderately reduces the risk (e.g., by 40-60%).
    • Component-Specific Vulnerabilities: Reduces risk proportionally to the severity of the specific vulnerability.

  • Currently Implemented:

    • Partial implementation in the core-components directory. Components are updated, but formal code review is inconsistent. CVE monitoring is in place for core AMP components.

  • Missing Implementation:

    • Formal, documented code review process for all AMP components, including third-party.
    • Consistent application of least privilege for AMP component attributes.
    • Automated testing of AMP component updates is not fully implemented.
    • Complete inventory of all used AMP components is incomplete.

Mitigation Strategy: Signed Exchanges (SXG) for AMP

  • Description: This entire strategy is inherently AMP-specific, as SXG is a technology designed to work with AMP Caches.

    1. Generate Key Pair: Create a key pair for signing AMP pages.
    2. Configure Server: Modify your server to generate SXG responses for AMP requests, including the necessary HTTP headers.
    3. Integrate with AMP Cache: Ensure compatibility with the AMP Caches you use.
    4. Monitor and Rotate Keys: Regularly monitor and rotate signing keys.
    5. Set short TTLs: Set short cache Time-To-Live values.

  • Threats Mitigated:

    • Cache Poisoning/Manipulation (High Severity): Specifically targets the vulnerability of AMP pages being served from potentially compromised AMP Caches.
    • Man-in-the-Middle (MitM) Attacks (High Severity): Protects AMP pages in transit between the origin and the AMP Cache.

  • Impact:

    • Cache Poisoning: Near-complete mitigation (95-100%).
    • MitM Attacks: Significant reduction in risk (80-90%).

  • Currently Implemented:

    • Not implemented.

  • Missing Implementation:

    • Entire SXG implementation is missing.

Mitigation Strategy: AMP-Specific Redirect Validation (within AMP Components)

  • Description: This focuses on validation within the context of AMP components, particularly amp-form.

    1. amp-form Attribute Validation: Scrutinize the action and action-xhr attributes of amp-form. These attributes directly control where the form data is sent and are specific to AMP.
    2. Whitelist (within AMP Context): Ideally, use a whitelist approach within the AMP component configuration (if possible, depending on the server-side setup) to restrict allowed action and action-xhr URLs. This is more restrictive than general server-side validation.
    3. Avoid User Input in action: Never allow user-provided input to directly influence the action or action-xhr attributes. This is a common vulnerability pattern within AMP forms.
    4. Sanitize and encode: Sanitize and encode all data that is used in AMP components.

  • Threats Mitigated:

    • Open Redirects via amp-form (Medium to High Severity): Directly addresses the misuse of amp-form for open redirect attacks.

  • Impact:

    • Open Redirects: Significant reduction in risk (70-90%) when combined with server-side validation. The AMP-specific focus prevents bypasses that might be possible with general validation alone.

  • Currently Implemented:

    • Partially implemented. Basic validation exists, but a strict, AMP-context whitelist is not used.

  • Missing Implementation:

    • Implementation of a whitelist approach within the AMP component configuration (if feasible).
    • More robust validation logic specifically targeting amp-form attributes.

Mitigation Strategy: AMP-Specific Content Security Policy (CSP)

  • Description: This is about crafting a CSP specifically tailored to the constraints and requirements of AMP.

    1. Define AMP-Tailored Policy: Create a CSP with directives optimized for AMP:
      • script-src: Restrict to 'self' and the required AMP CDN URLs (e.g., cdn.ampproject.org). This is crucial because AMP relies heavily on the CDN.
      • style-src: Similar restrictions, allowing the AMP CDN and being very careful with 'unsafe-inline'.
      • img-src: Control image sources, allowing the AMP CDN and trusted origins.
      • connect-src: Restrict to the API endpoints specifically used by your AMP components.
      • frame-ancestors: Use 'self' to prevent framing, as AMP itself restricts framing.
    2. Implement Header: Include the Content-Security-Policy header.
    3. Test with AMP Validator: Use the AMP Validator to ensure your CSP doesn't violate AMP's requirements. This is a key AMP-specific step.
    4. Use Reporting: Use report-uri or report-to to monitor CSP violations.

  • Threats Mitigated:

    • XSS (High Severity): Provides a crucial layer of defense against XSS, even if AMP component vulnerabilities exist. The AMP-specific CSP is more effective than a generic CSP.
    • Data Exfiltration (Medium to High Severity): Limits data exfiltration by restricting network connections made by AMP components.
    • Clickjacking/Framing (Medium Severity): Reinforces AMP's built-in framing restrictions.

  • Impact:

    • XSS: Moderate to significant reduction (50-80%).
    • Data Exfiltration: Moderate reduction (40-60%).
    • Clickjacking: Near-complete mitigation (95-100%).

  • Currently Implemented:

    • A basic CSP is implemented, but it is not comprehensive or AMP-specific.

  • Missing Implementation:

    • A strict, AMP-tailored CSP needs to be defined, implemented, and tested with the AMP Validator.
    • CSP reporting needs to be configured.

Mitigation Strategy: Secure amp-analytics and amp-pixel Configuration (AMP-Specific)

  • Description: This focuses on the security of AMP's built-in tracking components.

    1. Access Control (AMP Config): Strictly control access to the configuration of your amp-analytics and amp-pixel components. This is specific to how these AMP components are configured.
    2. Data Minimization (AMP Data): Collect only the minimum necessary data within the context of amp-analytics. Avoid collecting sensitive information that's not needed for AMP-specific tracking.
    3. Configuration Review (AMP-Specific): Regularly review the configuration of these AMP components to ensure they are not sending data to unexpected destinations.
    4. Traffic Monitoring (AMP Traffic): Monitor the network traffic generated by amp-analytics and amp-pixel to detect anomalies.

  • Threats Mitigated:

    • Data Exfiltration via AMP Tracking (Medium to High Severity): Reduces the risk of these AMP components being misused for data theft.

  • Impact:

    • Data Exfiltration: Moderate reduction in risk (40-60%).

  • Currently Implemented:

    • Basic access control is in place, but a formal review process is not consistently followed.

  • Missing Implementation:

    • Formal, documented review process for amp-analytics and amp-pixel configuration.
    • Implementation of network traffic monitoring specifically for these AMP components.
    • Consistent application of data minimization principles within the AMP analytics context.

Mitigation Strategy: Limit and Audit Third-Party AMP Extensions

  • Description:

    1. Minimize Usage: Only use third-party AMP extensions when absolutely necessary. Prefer official AMP components.
    2. Trusted Sources: Only obtain extensions from reputable sources.
    3. Code Review: Before using any third-party AMP extension, conduct a thorough code review.
    4. Regular Updates: Keep all third-party AMP extensions updated.
    5. Dependency Management: Use a dependency management system to track and manage third-party AMP extensions.

  • Threats Mitigated:

    • XSS via Extensions (High Severity): Reduces the risk of vulnerabilities introduced by third-party AMP code.
    • Data Exfiltration via Extensions (Medium to High Severity): Limits the potential for malicious AMP extensions to leak data.
    • Other Extension-Specific Vulnerabilities (Variable Severity): Addresses any vulnerabilities specific to the third-party AMP extension.

  • Impact:

    • XSS/Data Exfiltration/Other: Significantly reduces risk (potentially 70-90% reduction).

  • Currently Implemented:

    • No formal policy or process.

  • Missing Implementation:

    • All aspects of this mitigation strategy are currently missing.