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Mitigation Strategies Analysis for ruffle-rs/ruffle

Mitigation Strategy: Stay Up-to-Date and Monitor Security Advisories

Description:

  1. Subscribe to Ruffle Releases: Subscribe to Ruffle's official release announcements and security advisories (GitHub, mailing list, etc.). This is crucial for receiving timely notifications about security patches.
  2. Automated Dependency Updates: Use a dependency management tool (e.g., cargo for Rust, npm if using Ruffle.js) to automatically check for and install Ruffle updates. This ensures you're always running the latest, most secure version.
  3. Vulnerability Scanning: Integrate vulnerability scanning tools (e.g., cargo audit, Snyk, Dependabot) that specifically target Ruffle and its dependencies. This helps identify known vulnerabilities.
  4. Rapid Patching Process: Establish a process for quickly deploying Ruffle updates, especially security-related patches, to production environments. Minimize the time between vulnerability disclosure and patch deployment.

Threats Mitigated:

  • Ruffle-Specific Vulnerabilities: (Severity: High) - Addresses vulnerabilities discovered within the Ruffle codebase itself. This is the primary threat this strategy mitigates.

Impact:

  • Ruffle-Specific Vulnerabilities: Significantly reduces the risk of exploitation of Ruffle-specific bugs. The faster the update, the lower the risk. This is a critical mitigation.

Currently Implemented:

  • Example: Dependency management with cargo is used.
  • Example: Basic vulnerability scanning with cargo audit is in place.

Missing Implementation:

  • Example: Automated deployment of Ruffle updates is not fully automated.
  • Example: Subscription to Ruffle security advisories needs to be formalized.

Mitigation Strategy: Resource Limits (Within Ruffle/WebAssembly)

Description:

  1. WebAssembly Memory Limits: When instantiating the Ruffle WebAssembly module, set a reasonable maximum memory allocation. This is done through WebAssembly APIs (e.g., WebAssembly.Memory in JavaScript). This prevents a malicious SWF from consuming all available memory.
  2. Ruffle Configuration (if applicable): Check if Ruffle itself offers any configuration options to limit resource usage (e.g., maximum number of concurrent animations, limits on ActionScript execution time). If such options exist, use them.

Threats Mitigated:

  • Resource Exhaustion (DoS via SWF): (Severity: Medium) - Limits the impact of resource-intensive SWFs within the Ruffle/WebAssembly context.
  • Ruffle-Specific Vulnerabilities: (Severity: Medium) - Can partially mitigate some Ruffle vulnerabilities that might lead to excessive resource consumption.

Impact:

  • Resource Exhaustion: Reduces the likelihood of a successful DoS attack originating from within Ruffle.
  • Ruffle-Specific Vulnerabilities: Provides a limited degree of protection against vulnerabilities that manifest as resource exhaustion.

Currently Implemented:

  • Example: Basic WebAssembly memory limits are set in src/ruffle_wrapper.js.

Missing Implementation:

  • Example: Investigation into Ruffle-specific configuration options for resource limits is needed.

Mitigation Strategy: Strict Context Separation and Output Sanitization (Within Ruffle's Interaction)

Description:

  1. Controlled DOM Access: If Ruffle provides any APIs for interacting with the host page's DOM, use these APIs very sparingly and with extreme caution. Avoid direct DOM manipulation from within the emulated ActionScript environment if at all possible. If Ruffle provides specific, sandboxed methods for interacting with the DOM, use those exclusively.
  2. Output Sanitization (Ruffle-to-Host): If Ruffle outputs any data to the host page (e.g., text, HTML fragments), ensure that this output is passed through a robust HTML sanitization library before being inserted into the DOM. This is critical to prevent XSS. This sanitization should happen as close as possible to the point where Ruffle interacts with the host.
  3. ExternalInterface Whitelisting (If Used): If Ruffle supports ExternalInterface (the Flash-to-JavaScript communication mechanism), implement a very strict whitelist of allowed JavaScript functions that can be called from ActionScript. Never allow arbitrary JavaScript execution. Validate all data passed through ExternalInterface as if it were untrusted user input.

Threats Mitigated:

  • Cross-Site Scripting (XSS) via Emulated ActionScript: (Severity: High) - Prevents malicious SWFs from injecting JavaScript into the host page through Ruffle's interaction with the DOM or ExternalInterface.

Impact:

  • Cross-Site Scripting (XSS): Significantly reduces the risk of XSS, provided the sanitization and whitelisting are implemented correctly and comprehensively.

Currently Implemented:

  • Example: Basic output sanitization is used in src/ui_handler.js, but needs to be reviewed for completeness and placed closer to Ruffle's output.

Missing Implementation:

  • Example: ExternalInterface whitelisting is not fully implemented.
  • Example: A comprehensive review of all Ruffle-to-host interaction points is needed to ensure proper sanitization.

Mitigation Strategy: Disable Legacy Features and Enforce Modern Security Policies (Within Ruffle's Configuration)

Description:

  1. Identify Legacy Features: Thoroughly review Ruffle's documentation and configuration options to identify any legacy Flash features that are enabled by default but are not absolutely essential for the application's functionality. Examples might include LocalConnection, SharedObject, or older network APIs.
  2. Disable Unnecessary Features (Ruffle Config): Use Ruffle's configuration mechanisms (if available) to explicitly disable or restrict these unnecessary legacy features. This reduces the attack surface.
  3. Enforce Modern Security Policies (Ruffle Config): If Ruffle provides options to enforce modern security policies (like the Same-Origin Policy) even for SWFs designed for older Flash Player versions, enable these options. This ensures that Ruffle behaves as securely as possible, regardless of the SWF's intended environment.
  4. Configuration Review: Regularly review Ruffle's configuration (as the project evolves) to ensure that legacy features remain disabled and that security policies are up-to-date.

Threats Mitigated:

  • Bypassing of Same-Origin Policy (SOP): (Severity: High) - Prevents SWFs from exploiting legacy features to bypass the Same-Origin Policy.
  • Information Disclosure: (Severity: Medium) - Reduces the risk of SWFs accessing local resources or communicating with unauthorized domains by leveraging deprecated features.

Impact:

  • Bypassing of Same-Origin Policy (SOP): Significantly reduces the risk by enforcing modern security restrictions at the Ruffle level.
  • Information Disclosure: Reduces the attack surface by limiting access to potentially sensitive features within Ruffle's emulation.

Currently Implemented:

  • Example: Some legacy features are disabled by default in Ruffle's configuration.

Missing Implementation:

  • Example: A comprehensive review of all Ruffle configuration options related to legacy features and security policies is needed.
  • Example: Explicit configuration to enforce modern security policies in all cases, overriding any SWF-specific settings, is needed.