Skip to content

Latest commit

 

History

History
133 lines (112 loc) · 10.3 KB

attack-tree.md

File metadata and controls

133 lines (112 loc) · 10.3 KB

Attack Tree Analysis for ffmpegwasm/ffmpeg.wasm

Objective: To execute arbitrary code on the client's machine (browser) OR cause a Denial of Service (DoS) affecting the application's functionality related to ffmpeg.wasm, OR exfiltrate sensitive data processed by ffmpeg.wasm.

Attack Tree Visualization

Compromise Application via ffmpeg.wasm
    |
    -------------------------------------------------------------------------------------------------
    |                                               |                                               |
1. Execute Arbitrary Code                     2. Denial of Service (DoS)                  3. Data Exfiltration
    |                                               |                                               |
    -------------                                 -------------------                             -------------------
    |           |                                 |                 |                             |                 |
  1.1 WASM    1.2 Input                         2.1 Resource      2.2 Input                       -                 3.2 Memory
  Escape      Validation                        Exhaustion       Validation                      -                 Inspection
              Bypass                                            (Malicious Input)                                     (WASM)

1.1 WASM Escape
    |
    ------------------------
    |
1.1.2 Leverage ffmpeg.wasm Bug to Escape WASM Sandbox [CRITICAL]

1.2 Input Validation Bypass (to achieve code execution) [HIGH RISK]
    |
    --------------------------------------------------------------------------------
    |                                               |                               |
1.2.1 Fuzzing ffmpeg.wasm with Malformed          1.2.2 Exploit Codec-Specific     1.2.4 Integer/Buffer Overflow
      Media Files (various codecs) [CRITICAL]       Vulnerabilities (CVEs)         in ffmpeg.wasm's C code [CRITICAL]
                                                  [HIGH RISK]

2.1 Resource Exhaustion [HIGH RISK]
    |
    --------------------------------------------------------
    |                                               |
2.1.1 Memory Exhaustion (Large/Complex Files)   2.1.2 CPU Exhaustion (Complex
[CRITICAL]                                        Encoding/Decoding Operations)
                                                  [CRITICAL]
2.2 Input Validation (DoS)
    |
    --------------------------------------------------------
    |
    2.2.4 Trigger Pathological Case in ffmpeg's Algorithms [CRITICAL]

3.2 Memory Inspection (WASM)
    |
    --------------------------------------------------------
    |
    3.2.2 Leverage ffmpeg.wasm Bug to Read Arbitrary Memory within WASM [CRITICAL]

Attack Tree Path: 1. Execute Arbitrary Code

  • 1.1.2 Leverage ffmpeg.wasm Bug to Escape WASM Sandbox [CRITICAL]
    • Description: This involves finding a vulnerability within the ffmpeg.wasm code itself that allows an attacker to break out of the WebAssembly sandbox and execute arbitrary code in the browser's main execution context. This is a very serious vulnerability, as it bypasses the security guarantees of WebAssembly.
    • Example: A buffer overflow in the C code compiled to WASM, combined with a flaw in how memory is handled between the JavaScript wrapper and the WASM module, could allow overwriting critical data structures and hijacking control flow.
    • Mitigation:
      • Rigorous code auditing of ffmpeg.wasm, especially the interface between JavaScript and the compiled C code.
      • Use of memory-safe languages (e.g., Rust) for new code or critical components.
      • Extensive fuzzing targeting the WASM interface.
      • Sandboxing techniques beyond the standard WASM sandbox, if possible.

Attack Tree Path: 1.2 Input Validation Bypass (to achieve code execution) [HIGH RISK]

*   **1.2.1 Fuzzing ffmpeg.wasm with Malformed Media Files (various codecs) [CRITICAL]**
    *   **Description:** This involves systematically providing ffmpeg.wasm with a wide range of malformed, invalid, or unexpected media files (using various codecs) to trigger vulnerabilities like buffer overflows, integer overflows, or other memory corruption issues.
    *   **Example:** Crafting a specially designed MP4 file with an invalid header or corrupted data chunks that causes a buffer overflow in the H.264 decoder within ffmpeg.wasm.
    *   **Mitigation:**
        *   Integrate comprehensive fuzzing into the development and testing pipeline.
        *   Use multiple fuzzing tools (e.g., AFL, libFuzzer, specialized media fuzzers).
        *   Target a wide variety of codecs and file formats.
        *   Implement robust input validation before passing data to ffmpeg.wasm.

*   **1.2.2 Exploit Codec-Specific Vulnerabilities (CVEs) [HIGH RISK]**
    *   **Description:** This involves leveraging publicly known vulnerabilities (Common Vulnerabilities and Exposures - CVEs) in specific codecs used by FFmpeg. Attackers can use publicly available exploit code or create their own based on the CVE details.
    *   **Example:** A known buffer overflow vulnerability in a specific version of the libvpx library (used for VP8/VP9 encoding) could be exploited by providing a crafted WebM file.
    *   **Mitigation:**
        *   Stay up-to-date on CVEs related to FFmpeg and the codecs it uses.
        *   Disable or carefully restrict the use of codecs known to be problematic or have a history of vulnerabilities.
        *   Regularly update the underlying FFmpeg library used to build ffmpeg.wasm.
        *   Implement input validation to reject files that attempt to exploit known vulnerabilities.

*   **1.2.4 Integer/Buffer Overflow in ffmpeg.wasm's C code [CRITICAL]**
    *   **Description:** These are classic memory corruption vulnerabilities that can occur in C/C++ code due to incorrect handling of integer values or buffer sizes.  If these vulnerabilities exist in the FFmpeg code compiled to WASM, they can be exploited.
    *   **Example:** An integer overflow in a calculation related to frame size could lead to allocating an insufficient buffer, resulting in a buffer overflow when data is written to it.
    *   **Mitigation:**
        *   Employ static analysis tools to detect potential integer and buffer overflows.
        *   Use memory-safe languages or techniques (bounds checking, safe integer libraries, etc.).
        *   Thorough code review focusing on memory management and arithmetic operations.
        *   Fuzzing specifically designed to trigger integer and buffer overflows.

Attack Tree Path: 2. Denial of Service (DoS)

  • 2.1 Resource Exhaustion [HIGH RISK]

    • 2.1.1 Memory Exhaustion (Large/Complex Files) [CRITICAL]

      • Description: This involves providing ffmpeg.wasm with very large or complex media files that consume all available memory, causing the application to crash or become unresponsive.
      • Example: Uploading a multi-gigabyte video file or a file with an extremely high resolution or bit rate.
      • Mitigation:
        • Implement strict limits on input file size and complexity (resolution, bit rate, frame rate, etc.).
        • Use streaming processing where possible to avoid loading the entire file into memory at once.
        • Monitor memory usage and gracefully handle out-of-memory conditions (e.g., return an error, terminate the process).
        • Consider using Web Workers to isolate ffmpeg.wasm processing and prevent it from blocking the main thread.

    • 2.1.2 CPU Exhaustion (Complex Encoding/Decoding Operations) [CRITICAL]

      • Description: This involves using complex encoding or decoding operations that consume excessive CPU cycles, making the application unresponsive.
      • Example: Requesting a computationally expensive video transcoding operation with very high quality settings or using a complex codec with many features enabled.
      • Mitigation:
        • Limit the complexity of allowed encoding/decoding operations (e.g., restrict certain codecs, limit quality settings).
        • Implement timeouts to prevent long-running processes from blocking the application.
        • Use Web Workers to offload processing to separate threads.
        • Monitor CPU usage and throttle or terminate processes that consume excessive resources.

  • 2.2.4 Trigger Pathological Case in ffmpeg's Algorithms [CRITICAL]

    • Description: This involves crafting input that, while not necessarily malformed in a traditional sense, triggers a worst-case scenario in one of FFmpeg's algorithms, leading to excessive resource consumption or an infinite loop.
    • Example: A video file designed to exploit a specific weakness in a motion estimation algorithm, causing it to take an exceptionally long time to process.
    • Mitigation:
      • Thorough testing with a wide variety of inputs, including edge cases and "stress tests."
      • Code review and analysis of FFmpeg's algorithms to identify potential pathological cases.
      • Timeouts and resource limits to prevent runaway processes.

Attack Tree Path: 3. Data Exfiltration

  • 3.2.2 Leverage ffmpeg.wasm Bug to Read Arbitrary Memory within WASM [CRITICAL]
    • Description: This involves finding a vulnerability within ffmpeg.wasm that allows reading memory outside of intended bounds, but still within the confines of the WebAssembly sandbox. This could expose sensitive data being processed by ffmpeg.wasm.
    • Example: A buffer over-read vulnerability in a codec's parsing logic could allow reading adjacent memory within the WASM module, potentially revealing parts of other video frames or internal data structures.
    • Mitigation:
      • Rigorous code auditing and fuzzing, focusing on memory access patterns and array bounds checking.
      • Use of memory-safe languages or techniques to prevent out-of-bounds reads.
      • Careful management of sensitive data within the WASM module, avoiding storing it in predictable locations.