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Mitigation Strategies Analysis for element-hq/element-web

Mitigation Strategy: Enhanced End-to-End Encryption (E2EE) Verification (Client-Side)

  • Description:

    1. Developer Steps (element-web):
      • Modify the element-web UI to make the device verification process (cross-signing) a central part of the user onboarding flow.
      • Develop interactive, guided tutorials within the Element Web UI to explain device verification.
      • Implement prominent visual cues (icons, color-coded badges) within the Element Web UI to clearly indicate verification status.
        • Green: Verified
        • Yellow: Unverified
        • Red: Untrusted/Blacklisted
      • Display a clear, unavoidable warning message within the Element Web UI when sending to unverified devices.
      • Add periodic reminders (pop-up notifications within Element Web) to verify devices.
      • Implement "blacklist" or "distrust" device options in the Element Web UI.
      • Ensure secure storage and management of device verification keys within the Element Web client.
      • Consider implementing "TOFU" (Trust On First Use) with mandatory verification after a set period within the Element Web client.
      • Improve device management UI within Element Web.

  • Threats Mitigated:

    • Man-in-the-Middle (MITM) Attacks: (Severity: High)
    • Compromised Devices: (Severity: High)
    • Impersonation: (Severity: High)

  • Impact:

    • MITM Attacks: Significantly reduces risk.
    • Compromised Devices: Reduces impact.
    • Impersonation: Significantly reduces risk.

  • Currently Implemented:

    • Cross-signing and device verification are implemented.
    • Basic visual indicators exist.

  • Missing Implementation:

    • More prominent visual cues and warnings.
    • Guided, in-app tutorials.
    • Periodic verification reminders.
    • TOFU with mandatory verification.
    • Improved device management UI.

Mitigation Strategy: Strict Widget Sandboxing (Client-Side)

  • Description:

    1. Developer Steps (element-web):
      • Ensure all widgets are embedded within iframes within the Element Web application.
      • Apply the most restrictive sandbox attribute to these iframes:
        • sandbox="allow-scripts allow-same-origin allow-popups allow-forms allow-popups-to-escape-sandbox" (Adjust only as strictly necessary). Never allow allow-top-navigation without extreme caution and justification.
      • Implement a strict Content Security Policy (CSP) specifically for the widget iframes within element-web.
      • Develop a mechanism within element-web to verify the origin of widgets before loading.
      • Implement a granular permission model within element-web for widgets, controlling capabilities via postMessage API. Carefully validate all messages.
      • Provide clear documentation for widget developers on secure coding practices, specifically addressing element-web integration.

  • Threats Mitigated:

    • Cross-Site Scripting (XSS) in Widgets: (Severity: High)
    • Data Exfiltration: (Severity: High)
    • Phishing: (Severity: Medium-High)
    • Denial of Service (DoS): (Severity: Medium)

  • Impact:

    • XSS: Significantly reduces risk.
    • Data Exfiltration: Significantly reduces risk.
    • Phishing: Reduces risk.
    • DoS: Reduces risk.

  • Currently Implemented:

    • Widgets are loaded in iframes.
    • Some basic sandboxing likely exists.

  • Missing Implementation:

    • Most restrictive sandbox attribute.
    • Strict CSP for widget iframes.
    • Widget origin verification.
    • Granular permission model.

Mitigation Strategy: Robust Event Validation (Client-Side)

  • Description:

    1. Developer Steps (element-web):
      • Implement client-side validation of all incoming Matrix events within the Element Web client, before rendering:
        • Re-verify signatures and timestamps.
        • Check for inconsistencies in event data.
        • Sanitize and encode user-provided data within events to prevent XSS within the Element Web rendering logic.
      • Implement client-side rate limiting within Element Web to mitigate spam and DoS.
      • Log all client-side validation failures within Element Web (consider privacy implications).

  • Threats Mitigated:

    • Malicious Events: (Severity: High)
    • Spam: (Severity: Medium)
    • Denial of Service (DoS): (Severity: Medium)
    • Replay Attacks: (Severity: Medium)
    • Cross-Site Scripting (XSS): (Severity: High)

  • Impact:

    • Malicious Events: Significantly reduces risk.
    • Spam: Reduces impact.
    • DoS: Reduces impact.
    • Replay Attacks: Prevents.
    • XSS: Significantly reduces risk.

  • Currently Implemented:

    • Some event validation likely exists.

  • Missing Implementation:

    • Comprehensive validation of all event fields.
    • Client-side rate limiting.
    • Robust logging of validation failures.

Mitigation Strategy: Automated Dependency Scanning and Updates (Development Process)

  • Description:

    1. Developer Steps (element-web build process):
      • Integrate a software composition analysis (SCA) tool (Snyk, Dependabot, OWASP Dependency-Check) into the element-web CI/CD pipeline.
      • Configure the SCA tool to scan all element-web dependencies for vulnerabilities.
      • Set up automated alerts for the element-web development team.
      • Establish a process for regularly updating element-web's dependencies.
      • Use dependency pinning (e.g., package-lock.json) in the element-web project.
      • Thoroughly test element-web after major dependency updates.

  • Threats Mitigated:

    • Vulnerabilities in Third-Party Libraries: (Severity: Variable, potentially High)

  • Impact:

    • Vulnerabilities in Third-Party Libraries: Significantly reduces risk.

  • Currently Implemented:

    • Likely some dependency management.

  • Missing Implementation:

    • Automated dependency scanning.
    • Formalized update process.
    • Automated alerts.

Mitigation Strategy: Client-Side State Manipulation Prevention

  • Description:

    1. Developer Steps (element-web):
      • Implement checks within the Element Web client to ensure client-side state consistency with received events. Detect and handle inconsistencies.
      • Use checksums or other data integrity mechanisms within the Element Web client to verify the integrity of critical client-side data.
      • Explore tamper-proofing techniques for the Element Web client code (obfuscation, integrity checks - with the understanding that these are not foolproof).

  • Threats Mitigated: * Client-Side State Manipulation: (Severity: Medium-High) - Attackers attempting to modify the client's view of the Matrix world, potentially leading to incorrect display of information or exploitation of logic flaws.

  • Impact:

    • Client-Side State Manipulation: Reduces the likelihood of successful attacks and makes exploitation more difficult.

  • Currently Implemented:

    • Limited state validation may exist.

  • Missing Implementation:

    • Comprehensive state consistency checks.
    • Data integrity mechanisms for critical data.
    • Tamper-proofing techniques.