Skip to content

Latest commit

 

History

History
50 lines (41 loc) · 7.33 KB

threat-modeling.md

File metadata and controls

50 lines (41 loc) · 7.33 KB

Threat Model Analysis for fizzed/font-mfizz

Threat: Malicious SVG Injection (Code Execution)

  • Description: An attacker crafts a malicious SVG file containing embedded scripts or exploits targeting vulnerabilities in the SVG parsing library used by font-mfizz (e.g., a vulnerability in a library like resvg or a similar dependency, if and how it's used internally by font-mfizz). The attacker uploads this file, aiming for code execution on the server through the processing done by font-mfizz.
  • Impact: Remote Code Execution (RCE) on the server hosting the font-mfizz processing. This could lead to complete system compromise.
  • Affected Component: SVG parsing module/library within font-mfizz or its directly used dependencies (e.g., a hypothetical parseSVG() function or an underlying library like resvg if and only if font-mfizz uses it for parsing). The key here is that the exploit happens during font-mfizz's processing of the SVG.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict SVG Sanitization: Use a dedicated, security-focused SVG sanitizer before passing the SVG to font-mfizz. This sanitizer should remove all script tags, event handlers, external references, and any potentially dangerous elements or attributes. Whitelist allowed elements and attributes rather than blacklisting. This is the primary defense.
    • Dependency Auditing: Regularly audit font-mfizz and all its direct dependencies (especially the SVG parsing library it uses) for known vulnerabilities. Use tools like npm audit or similar for your package manager.
    • Sandboxing: Run the font-mfizz processing in a sandboxed environment (e.g., Docker container, a restricted user account with minimal privileges) to limit the impact of a successful exploit.
    • Input Validation (Schema): Validate the SVG input against a strict XML schema that defines the allowed structure and content. Reject any SVG that doesn't conform to the schema.

Threat: Malicious SVG Injection (Denial of Service - Resource Exhaustion)

  • Description: An attacker uploads a very large or complex SVG file (e.g., with deeply nested elements, excessive numbers of paths, or extremely large dimensions) designed to consume excessive server resources (CPU, memory, disk space) during processing by font-mfizz.
  • Impact: Denial of Service (DoS). The application becomes unresponsive or crashes, preventing legitimate users from accessing it.
  • Affected Component: SVG parsing and font generation modules within font-mfizz (e.g., functions responsible for parsing the SVG structure and converting it to font data). The attack directly targets font-mfizz's processing capabilities.
  • Risk Severity: High
  • Mitigation Strategies:
    • Input Size Limits: Enforce strict limits on the maximum file size of uploaded SVGs before they are processed by font-mfizz.
    • Complexity Limits: Implement limits on the complexity of the SVG before passing it to font-mfizz, such as the maximum number of elements, attributes, nested levels, and path points.
    • Resource Limits (OS Level): Configure operating system-level resource limits (e.g., using ulimit on Linux) for the process running font-mfizz to prevent it from consuming excessive memory or CPU time.
    • Timeouts: Set a reasonable timeout for the font-mfizz processing. If the process exceeds the timeout, terminate it.
    • Rate Limiting: If users can upload SVGs, implement rate limiting to prevent an attacker from flooding the server with requests intended for font-mfizz.

Threat: Malicious SVG Injection (Denial of Service - Algorithm Complexity)

  • Description: An attacker crafts an SVG file that, while not necessarily large, exploits algorithmic complexities in the SVG parsing or font generation process within font-mfizz or its directly used dependencies. This could involve specific combinations of SVG features that trigger worst-case performance scenarios in the underlying libraries as they are used by font-mfizz.
  • Impact: Denial of Service (DoS). Similar to resource exhaustion, but achieved through clever exploitation of algorithm weaknesses rather than brute force, directly impacting font-mfizz's processing.
  • Affected Component: SVG parsing and font generation algorithms within font-mfizz and its directly used dependencies. This is highly dependent on the specific implementation details of font-mfizz.
  • Risk Severity: High
  • Mitigation Strategies:
    • Fuzz Testing: Use fuzz testing techniques to identify input that triggers unexpectedly long processing times or high resource consumption within font-mfizz. This involves providing font-mfizz with a wide range of randomly generated or mutated SVG inputs.
    • Profiling: Profile the font-mfizz code during processing to identify performance bottlenecks and potential algorithmic complexity vulnerabilities within its own code and how it uses its dependencies.
    • Input Validation (Specific Features): If specific SVG features are identified as being particularly vulnerable to algorithmic complexity attacks when processed by font-mfizz, consider disallowing or strictly limiting their use before the SVG reaches font-mfizz.
    • Timeouts (again): Timeouts are crucial for mitigating this type of DoS, specifically within the context of font-mfizz's processing.

Threat: Dependency Vulnerabilities (Directly Used)

  • Description: A vulnerability exists in one of the libraries that font-mfizz directly depends on and actively uses (e.g., an XML parsing library, a font manipulation library). This vulnerability could be exploited through a crafted SVG file that is processed by font-mfizz. The key distinction is that the vulnerability is triggered during font-mfizz's operation, not through a separate attack vector.
  • Impact: Varies depending on the vulnerability, but could range from DoS to RCE, all stemming from font-mfizz's use of the vulnerable dependency.
  • Affected Component: Any of font-mfizz's direct and actively used dependencies.
  • Risk Severity: Varies (High to Critical) depending on the specific dependency and vulnerability, but we're filtering for High/Critical here.
  • Mitigation Strategies:
    • Dependency Auditing (Continuous): Continuously monitor direct dependencies for known vulnerabilities using tools like npm audit, yarn audit, or dedicated vulnerability scanners. Focus on dependencies that are involved in SVG parsing and font generation.
    • Regular Updates: Keep font-mfizz and all its direct dependencies updated to the latest versions.
    • Dependency Pinning (with Caution): Consider pinning direct dependency versions to specific, known-good releases, but be aware that this can prevent you from receiving security updates. A better approach is to use a lockfile (e.g., package-lock.json or yarn.lock) to ensure consistent dependency resolution, and regularly update the lockfile.