threat-modeling.md

Threat Model Analysis for ffmpegwasm/ffmpeg.wasm

Threat: Malicious Media File Upload - Buffer Overflow

• Description: An attacker uploads a specially crafted media file designed to exploit a buffer overflow vulnerability in FFmpeg's C/C++ code during parsing or decoding within ffmpeg.wasm. This could involve overflowing a buffer on the stack or heap to overwrite memory regions and potentially gain control of program execution.
• Impact: Critical. Could lead to arbitrary code execution within the WebAssembly sandbox, potentially allowing the attacker to bypass sandbox restrictions and gain control over the browser process or access sensitive data within the browser context. In less severe cases, it could lead to browser crashes or unexpected application behavior.
• Affected Component: FFmpeg core libraries (decoders, demuxers, parsers) within ffmpeg.wasm. Specifically, vulnerable C/C++ code compiled to WebAssembly.
• Risk Severity: Critical
• Mitigation Strategies:
  • Input Validation: Implement robust input validation on the server-side and client-side before passing media files to ffmpeg.wasm. This includes file type validation, size limits, and potentially more advanced checks if feasible.
  • Regular ffmpeg.wasm Updates: Keep ffmpeg.wasm updated to the latest version to patch known vulnerabilities in upstream FFmpeg. Monitor FFmpeg security advisories and update promptly.
  • Content Security Policy (CSP): Implement a strict CSP to limit the capabilities of the application and reduce the potential impact of code execution vulnerabilities.
  • Sandbox Reinforcement (Browser): Rely on browser's WebAssembly sandbox for isolation. Ensure the browser is up-to-date to benefit from the latest sandbox security features.

Threat: Malicious Media File Upload - Denial of Service (Resource Exhaustion)

• Description: An attacker uploads a media file crafted to be computationally expensive to process by ffmpeg.wasm. This file could contain complex codecs, extremely high resolutions, or other features that force FFmpeg to consume excessive CPU and memory resources during decoding or processing. The attacker aims to overload the user's browser, causing slowdowns, freezes, or crashes.
• Impact: High. Denial of Service for the user. Degrades user experience, potentially rendering the application unusable. Can lead to browser crashes and data loss if the user is working on other tasks in the browser.
• Affected Component: FFmpeg core libraries (decoders, filters) within ffmpeg.wasm. Specifically, resource-intensive processing within FFmpeg's algorithms.
• Risk Severity: High
• Mitigation Strategies:
  • Input Validation and Limits: Implement limits on file size, resolution, and processing time. Reject files exceeding these limits.
  • Resource Monitoring (Client-Side): Monitor browser resource usage (CPU, memory) during ffmpeg.wasm processing. Implement mechanisms to stop processing if resource consumption becomes excessive.
  • Progress Indicators and Cancellation: Provide clear progress indicators and allow users to cancel long-running ffmpeg.wasm tasks to prevent prolonged resource exhaustion.
  • Throttling/Queueing: If the application allows multiple concurrent ffmpeg.wasm tasks, implement throttling or queueing to limit the number of simultaneous processes and prevent resource overload.

Threat: Supply Chain Compromise - Malicious ffmpeg.wasm Package

• Description: An attacker compromises the ffmpeg.wasm package in a package registry (e.g., npm). This could involve injecting malicious code into the package during the build process or by directly tampering with the published package. When developers install this compromised package, the malicious code is included in their application.
• Impact: Critical. If the ffmpeg.wasm package is compromised, the attacker can inject arbitrary JavaScript code into the application, gaining full control over the application's client-side execution environment. This could lead to data theft, user account compromise, or further attacks.
• Affected Component: Entire ffmpeg.wasm package and its distribution mechanism (package registry).
• Risk Severity: Critical
• Mitigation Strategies:
  • Verify Package Integrity: Use package integrity checks (e.g., npm audit, yarn audit, checksum verification) to ensure the downloaded ffmpeg.wasm package has not been tampered with.
  • Use Reputable Sources: Obtain ffmpeg.wasm from trusted and reputable sources.
  • Dependency Scanning: Use dependency scanning tools to detect known vulnerabilities in ffmpeg.wasm and its dependencies.
  • Software Bill of Materials (SBOM): Consider using SBOM tools to track the components of ffmpeg.wasm and its build process for better supply chain visibility.
  • Subresource Integrity (SRI): If loading ffmpeg.wasm from a CDN, use SRI to ensure the integrity of the loaded file.

Threat: Upstream FFmpeg Vulnerability - Unpatched in ffmpeg.wasm

• Description: A new security vulnerability is discovered in upstream FFmpeg. If the ffmpeg.wasm library is not promptly updated to include the fix for this vulnerability, applications using the outdated ffmpeg.wasm remain vulnerable to attacks exploiting this flaw.
• Impact: High to Critical, depending on the severity of the upstream vulnerability. Could lead to buffer overflows, arbitrary code execution, or other security breaches, similar to the "Malicious Media File Upload - Buffer Overflow" threat.
• Affected Component: FFmpeg core libraries within ffmpeg.wasm that contain the unpatched vulnerability.
• Risk Severity: High to Critical (depending on the specific vulnerability)
• Mitigation Strategies:
  • Regular ffmpeg.wasm Updates: Establish a process for regularly monitoring FFmpeg security advisories and updating ffmpeg.wasm to the latest version as soon as updates are available.
  • Vulnerability Scanning: Periodically scan the application's dependencies, including ffmpeg.wasm, for known vulnerabilities using vulnerability scanning tools.
  • Proactive Monitoring: Monitor security news and vulnerability databases for reports of new FFmpeg vulnerabilities.