mitigations.md

Mitigation Strategies Analysis for ffmpegwasm/ffmpeg.wasm

Mitigation Strategy: Subresource Integrity (SRI) for ffmpeg.wasm

• Description:

  1. Generate the SRI hash for the ffmpeg.wasm file you intend to use. This can be done using online SRI hash generators or command-line tools like openssl dgst -sha384 -binary ffmpeg.wasm | openssl base64 -no-newlines.
  2. When including ffmpeg.wasm in your HTML using a <script> tag, add the integrity attribute with the generated hash and the crossorigin="anonymous" attribute.
  3. Example: <script src="https://cdn.example.com/ffmpeg.wasm" integrity="sha384-YOUR_GENERATED_HASH" crossorigin="anonymous"></script>
  4. Ensure the hash is updated whenever you update the ffmpeg.wasm version.

• List of Threats Mitigated:

  • CDN Compromise/Man-in-the-Middle Attacks (High Severity): An attacker compromises the CDN or intercepts the network request to replace ffmpeg.wasm with a malicious version, leading to execution of untrusted code within the browser via ffmpeg.wasm.
  • File Tampering (High Severity): If self-hosting, an attacker gains access to your server and modifies the ffmpeg.wasm file, again leading to execution of a compromised ffmpeg.wasm in the browser.

• Impact:

  • CDN Compromise/Man-in-the-Middle Attacks: High reduction. SRI ensures the browser verifies the integrity of the fetched ffmpeg.wasm file, preventing execution of a compromised script.
  • File Tampering: High reduction. SRI, if implemented correctly and the hash is securely managed, prevents execution of a tampered ffmpeg.wasm file.

• Currently Implemented:

  • Implemented in the project's index.html file when loading ffmpeg.wasm from a CDN. The SRI hash is generated during the build process and automatically injected into the HTML.

• Missing Implementation:

  • Not applicable as SRI is implemented for CDN loading. If the project were to switch to self-hosting ffmpeg.wasm, SRI should also be implemented for the self-hosted file.

Mitigation Strategy: Regular ffmpeg.wasm Updates

• Description:

  1. Subscribe to the ffmpegwasm/ffmpeg.wasm GitHub repository's release notifications or security advisories.
  2. Periodically check for new releases of ffmpeg.wasm on the official repository or npm (if using npm package).
  3. Review release notes and security advisories for each new version to understand the changes and security patches included in ffmpeg.wasm itself or its underlying FFmpeg version.
  4. Update the ffmpeg.wasm dependency in your project to the latest stable version.
  5. Thoroughly test your application after updating ffmpeg.wasm to ensure compatibility and no regressions are introduced in your application's interaction with the updated ffmpeg.wasm.

• List of Threats Mitigated:

  • Exploitation of Known Vulnerabilities in FFmpeg/WASM (High Severity): Older versions of ffmpeg.wasm may contain known security vulnerabilities inherited from underlying FFmpeg or introduced during the WASM compilation process. Attackers could exploit these vulnerabilities if present in the ffmpeg.wasm version used by the application.

• Impact:

  • Exploitation of Known Vulnerabilities in FFmpeg/WASM: High reduction. Updating to the latest ffmpeg.wasm version patches known vulnerabilities within ffmpeg.wasm and its core FFmpeg, significantly reducing the attack surface.

• Currently Implemented:

  • Partially implemented. The development team has a reminder to check for updates monthly, but the process is manual and not consistently followed for ffmpeg.wasm specifically.

• Missing Implementation:

  • Automate the update process for ffmpeg.wasm by integrating dependency vulnerability scanning tools into the CI/CD pipeline that specifically monitor ffmpeg.wasm and its dependencies.
  • Implement automated testing to run after ffmpeg.wasm updates to quickly identify regressions in application functionality related to ffmpeg.wasm.

Mitigation Strategy: Input File Type Whitelisting for ffmpeg.wasm Processing

• Description:

  1. Define a strict whitelist of allowed input file types (e.g., .mp4, .webm, .mov) that your application will process using ffmpeg.wasm.
  2. Implement client-side validation (JavaScript) to check the file extension of uploaded files against the whitelist before passing them to ffmpeg.wasm.
  3. Implement server-side validation (if files are uploaded to a server before ffmpeg.wasm processing) to re-verify the file type and potentially use file magic number checks for more robust validation before allowing ffmpeg.wasm to process them.
  4. Reject files that do not match the allowed file types and provide informative error messages to the user, preventing them from being processed by ffmpeg.wasm.

• List of Threats Mitigated:

  • Processing of Malicious Files by ffmpeg.wasm (Medium to High Severity): Users might upload files specifically crafted to exploit vulnerabilities in FFmpeg's processing of certain file formats or container formats when handled by ffmpeg.wasm.
  • Denial of Service (DoS) via Resource Exhaustion in ffmpeg.wasm (Medium Severity): Processing unexpected or malformed file types by ffmpeg.wasm could lead to excessive resource consumption within the browser, causing application slowdown or crashes due to ffmpeg.wasm operations.

• Impact:

  • Processing of Malicious Files by ffmpeg.wasm: Medium to High reduction. Whitelisting reduces the attack surface for ffmpeg.wasm by limiting the types of files it processes, making it harder to exploit format-specific vulnerabilities within ffmpeg.wasm/FFmpeg.
  • Denial of Service (DoS) via Resource Exhaustion in ffmpeg.wasm: Medium reduction. Restricting file types can prevent ffmpeg.wasm from processing file formats known to be resource-intensive or problematic for FFmpeg, mitigating DoS risks related to ffmpeg.wasm usage.

• Currently Implemented:

  • Client-side validation is implemented in JavaScript to check file extensions against a basic whitelist (.mp4, .webm) before files are processed by ffmpeg.wasm.

• Missing Implementation:

  • Server-side validation is missing. Files are directly passed to ffmpeg.wasm in the browser after client-side validation, without server-side re-verification before ffmpeg.wasm processing.
  • File magic number validation is not implemented for more robust file type verification before ffmpeg.wasm processing.

Mitigation Strategy: Input File Size Limits for ffmpeg.wasm Processing

• Description:

  1. Determine reasonable maximum file size limits for input files that will be processed by ffmpeg.wasm, based on your application's use case and available browser resources for ffmpeg.wasm operations.
  2. Implement client-side validation (JavaScript) to check the file size of uploaded files before passing them to ffmpeg.wasm for processing.
  3. Implement server-side validation (if applicable) to re-verify file size limits before allowing ffmpeg.wasm to process the files.
  4. Reject files exceeding the size limits and provide informative error messages to the user, preventing ffmpeg.wasm from attempting to process them.

• List of Threats Mitigated:

  • Denial of Service (DoS) via Resource Exhaustion in ffmpeg.wasm (High Severity): Users might upload extremely large files that, when processed by ffmpeg.wasm, consume excessive browser memory and CPU, leading to application crashes or browser freezes specifically due to ffmpeg.wasm operations.

• Impact:

  • Denial of Service (DoS) via Resource Exhaustion in ffmpeg.wasm: High reduction. Limiting file sizes directly prevents ffmpeg.wasm from processing excessively large files, mitigating resource exhaustion attacks specifically targeting ffmpeg.wasm operations.

• Currently Implemented:

  • Client-side file size limit of 100MB is implemented in JavaScript, preventing files larger than this from being processed by ffmpeg.wasm.

• Missing Implementation:

  • Server-side file size validation is missing, meaning if client-side validation is bypassed, there's no server-side check before ffmpeg.wasm processing (if files are uploaded to a server first).
  • The file size limit for ffmpeg.wasm processing is a fixed value and not configurable based on user roles or application load related to ffmpeg.wasm usage.

Mitigation Strategy: Command Argument Sanitization for ffmpeg.wasm

• Description:

  1. Identify all user-controlled inputs that are used to construct ffmpeg.wasm commands (e.g., filenames, format options, filters passed to ffmpeg.wasm).
  2. Implement robust sanitization and escaping of these inputs before passing them as arguments to ffmpeg.wasm commands.
  3. Use parameterized commands or command-line argument parsing libraries if available in ffmpeg.wasm (though direct parameterization might be limited in ffmpeg.wasm).
  4. Specifically, escape shell-sensitive characters (e.g., ;, &, |, $, `, \, *, ?, ~, !, {, }, (, ), <, >, ^, ", ', [, ], #, , \t, \n, \r, \f) to prevent command injection vulnerabilities within the ffmpeg.wasm command execution context.
  5. Consider using whitelisting for allowed command options and values passed to ffmpeg.wasm instead of blacklisting dangerous characters.

• List of Threats Mitigated:

  • Command Injection in ffmpeg.wasm Commands (High Severity): Attackers might manipulate user inputs to inject malicious commands into the ffmpeg.wasm command line. While the browser sandbox limits the impact, command injection could still lead to unexpected behavior, data manipulation within the ffmpeg.wasm context, or potentially sandbox escapes in vulnerable browser versions (though less likely with WASM).

• Impact:

  • Command Injection in ffmpeg.wasm Commands: High reduction. Proper sanitization and escaping of command arguments effectively prevents command injection attacks within ffmpeg.wasm command execution by neutralizing malicious characters.

• Currently Implemented:

  • Basic sanitization is implemented by replacing spaces in filenames with underscores before passing them to ffmpeg.wasm commands.

• Missing Implementation:

  • Comprehensive escaping of all shell-sensitive characters is not implemented for arguments passed to ffmpeg.wasm.
  • Whitelisting of allowed command options for ffmpeg.wasm is not implemented.
  • No dedicated command-line argument parsing library is used for constructing ffmpeg.wasm commands.

Mitigation Strategy: Timeout for ffmpeg.wasm Operations

• Description:

  1. Implement a timeout mechanism for all ffmpeg.wasm operations.
  2. Set a reasonable timeout duration based on the expected processing time for typical ffmpeg.wasm operations and the application's performance requirements related to ffmpeg.wasm usage.
  3. Use Promise.race with a timeout promise and the ffmpeg.wasm operation promise to enforce the timeout for ffmpeg.wasm commands.
  4. If the timeout is reached, terminate the ffmpeg.wasm operation gracefully, display an error message to the user indicating a timeout in ffmpeg.wasm processing, and prevent further resource consumption by the timed-out ffmpeg.wasm command.

• List of Threats Mitigated:

  • Denial of Service (DoS) via Resource Exhaustion from ffmpeg.wasm (Medium Severity): Malicious or unexpected inputs could cause ffmpeg.wasm operations to run indefinitely, consuming browser resources and leading to DoS specifically due to prolonged ffmpeg.wasm execution.
  • Runaway ffmpeg.wasm Processes (Medium Severity): Bugs or unexpected behavior in ffmpeg.wasm itself or the application logic could lead to ffmpeg.wasm operations that never complete, tying up browser resources allocated to ffmpeg.wasm.

• Impact:

  • Denial of Service (DoS) via Resource Exhaustion from ffmpeg.wasm: Medium reduction. Timeouts prevent ffmpeg.wasm operations from running indefinitely, limiting resource consumption in DoS scenarios caused by ffmpeg.wasm.
  • Runaway ffmpeg.wasm Processes: Medium reduction. Timeouts act as a safety net to terminate ffmpeg.wasm operations that get stuck due to bugs or unexpected conditions within ffmpeg.wasm or its interaction with the application.

• Currently Implemented:

  • No timeout mechanism is currently implemented for ffmpeg.wasm operations.

• Missing Implementation:

  • Timeout needs to be implemented for all ffmpeg.wasm command executions.
  • The timeout duration for ffmpeg.wasm operations should be configurable and potentially adjustable based on the type of ffmpeg.wasm operation being performed.