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Attack Tree Analysis for mozilla/mozjpeg

Objective: Execute Arbitrary Code or Cause DoS via mozjpeg

Attack Tree Visualization

Root: Execute Arbitrary Code or Cause DoS via mozjpeg

    ├── OR
    │   ├── AND: Integer Overflow in DCT Coefficient Handling [CN]
    │   │   ├── Vulnerability: Integer overflow in handling of DCT coefficients.
    │   │   ├── Exploit: Craft malicious JPEG with crafted DCT coefficients.
    │   │   ├── Mitigation: Rigorous input validation, bounds checking, safe integer arithmetic, fuzz testing.
    │   │   ├── Likelihood: Low
    │   │   ├── Impact: High
    │   │   ├── Effort: High
    │   │   ├── Skill Level: High
    │   │   └── Detection Difficulty: Medium
    │   │   └── AND
    │   │       ├── Trigger the overflow.
    │   │       └── Exploit the resulting memory corruption. [CN]
    │   ├── AND: Buffer Overflow in Marker Parsing [CN]
    │   │   ├── Vulnerability: Buffer overflow in parsing JPEG markers.
    │   │   ├── Exploit: Craft malicious JPEG with oversized/malformed marker.
    │   │   ├── Mitigation: Strict bounds checking, memory-safe parsing, fuzz testing.
    │   │   ├── Likelihood: Low
    │   │   ├── Impact: High
    │   │   ├── Effort: Medium
    │   │   ├── Skill Level: Medium/High
    │   │   └── Detection Difficulty: Medium
    │   │   └── AND
    │   │       ├── Trigger the overflow.
    │   │       └── Exploit the resulting memory corruption. [CN]
    │   ├── AND: Out-of-Bounds Read in Huffman Decoding [CN]
    │   │   ├── Vulnerability: Out-of-bounds read during Huffman decoding.
    │   │   ├── Exploit: Craft malicious JPEG with corrupted Huffman table/data.
    │   │   ├── Mitigation: Validate Huffman tables, bounds checking, fuzz testing.
    │   │   ├── Likelihood: Low
    │   │   ├── Impact: High
    │   │   ├── Effort: Medium/High
    │   │   ├── Skill Level: Medium/High
    │   │   └── Detection Difficulty: Medium
    │   │   └── AND
    │   │       ├── Trigger the out-of-bounds read.
    │   │       └── Exploit the resulting memory corruption/leak. [CN]
    │   ├── AND: Use-After-Free in Memory Management [CN]
    │   │   ├── Vulnerability: Use-after-free in memory management.
    │   │   ├── Exploit: Craft sequence of operations to trigger use-after-free.
    │   │   ├── Mitigation: Memory safety tools, code review, robust allocator.
    │   │   ├── Likelihood: Low
    │   │   ├── Impact: High
    │   │   ├── Effort: High
    │   │   ├── Skill Level: High
    │   │   └── Detection Difficulty: High
    │   │   └── AND
    │   │       ├── Trigger the use-after-free.
    │   │       └── Exploit the resulting memory corruption. [CN]
    │   └── AND: Denial of Service via Excessive Resource Consumption [HR]
    │       ├── Vulnerability:  mozjpeg forced to consume excessive resources.
    │       ├── Exploit: Craft complex JPEG to exhaust resources.
    │       ├── Mitigation:  Resource limits, rate limiting, monitoring.
    │       ├── Likelihood: Medium
    │       ├── Impact: Medium
    │       ├── Effort: Low
    │       ├── Skill Level: Low
    │       └── Detection Difficulty: Low
    │       └── AND
    │           ├── Provide a specially crafted image. [CN]
    │           └── Exhaust server resources. [CN]

Attack Tree Path: Integer Overflow in DCT Coefficient Handling [CN]

  • Vulnerability Description:
    • mozjpeg performs calculations on Discrete Cosine Transform (DCT) coefficients during image compression and decompression. Integer overflows can occur if these calculations result in values exceeding the maximum or minimum representable value for the integer type used.
  • Exploit Scenario:
    • An attacker crafts a JPEG image with carefully chosen DCT coefficients. These coefficients are designed to, when processed by mozjpeg's quantization or dequantization routines, trigger an integer overflow.
    • The overflow leads to a buffer overflow or other memory corruption.
    • The attacker then exploits this memory corruption to gain control of the program's execution flow, potentially leading to arbitrary code execution.
  • Mitigation Strategies:
    • Rigorous Input Validation: Validate DCT coefficients to ensure they fall within expected ranges.
    • Bounds Checking: Implement strict bounds checking during calculations on DCT coefficients.
    • Safe Integer Arithmetic: Use libraries or techniques that prevent integer overflows (e.g., SafeInt).
    • Fuzz Testing: Use fuzzing tools to provide a wide range of inputs, including malformed DCT coefficients, to identify potential overflow vulnerabilities.

Attack Tree Path: Buffer Overflow in Marker Parsing [CN]

  • Vulnerability Description:
    • JPEG images contain markers (e.g., SOF, DHT, DQT) that define various aspects of the image. mozjpeg parses these markers to understand the image structure. A buffer overflow can occur if a marker's length is larger than the buffer allocated to store it.
  • Exploit Scenario:
    • An attacker creates a JPEG image with a maliciously crafted marker. This marker might have an excessively large length field or contain malformed data.
    • When mozjpeg attempts to parse this marker, it writes data beyond the allocated buffer, overwriting adjacent memory.
    • This memory corruption can be exploited to redirect program execution to attacker-controlled code.
  • Mitigation Strategies:
    • Strict Bounds Checking: Verify the length of each marker before reading its data, ensuring it doesn't exceed the allocated buffer size.
    • Memory-Safe Parsing: Use memory-safe languages or libraries for parsing markers.
    • Fuzz Testing: Fuzz the marker parsing routines with a variety of malformed and oversized markers.

Attack Tree Path: Out-of-Bounds Read in Huffman Decoding [CN]

  • Vulnerability Description:
    • mozjpeg uses Huffman coding for entropy encoding of image data. An out-of-bounds read can occur if the Huffman decoder attempts to read data beyond the boundaries of the allocated memory buffer. This can happen due to a corrupted Huffman table or malformed compressed data.
  • Exploit Scenario:
    • An attacker provides a JPEG image with a corrupted Huffman table or manipulated compressed data.
    • During decoding, the Huffman decoder, guided by the corrupted table or data, attempts to read memory outside the allocated buffer.
    • This can lead to information leakage (reading arbitrary memory) or a crash, which might be further exploitable.
  • Mitigation Strategies:
    • Robust Validation of Huffman Tables: Thoroughly validate Huffman tables before using them for decoding.
    • Careful Bounds Checking: Implement strict bounds checking during the decoding process to prevent reads beyond the buffer's limits.
    • Fuzz Testing: Fuzz the Huffman decoding routines with various corrupted Huffman tables and data.

Attack Tree Path: Use-After-Free in Memory Management [CN]

  • Vulnerability Description:
    • A use-after-free vulnerability occurs when a program attempts to use memory that has already been freed. This can happen due to errors in memory allocation and deallocation logic.
  • Exploit Scenario:
    • An attacker crafts a sequence of JPEG processing operations (potentially involving multiple images or progressive decoding) that triggers a use-after-free condition within mozjpeg's memory management routines.
    • After a memory block is freed, the program (due to a bug) attempts to access it again.
    • This can lead to unpredictable behavior, including crashes or, more seriously, the ability to execute arbitrary code if the attacker can control the contents of the freed memory.
  • Mitigation Strategies:
    • Memory Safety Tools: Use tools like AddressSanitizer and Valgrind during development and testing to detect use-after-free errors.
    • Careful Code Review: Thoroughly review the memory management routines for potential use-after-free vulnerabilities.
    • Robust Memory Allocator: Consider using a more robust memory allocator that can help detect and prevent use-after-free errors.

Attack Tree Path: Denial of Service via Excessive Resource Consumption [HR]

  • Vulnerability Description:
    • mozjpeg, like any image processing library, consumes CPU and memory resources during decoding. An attacker can craft a malicious JPEG image that is designed to consume an excessive amount of these resources, leading to a denial-of-service (DoS).
  • Exploit Scenario:
    • An attacker creates a JPEG image that is extremely complex to decode. This could involve:
      • Very high resolution.
      • Extremely high compression ratios.
      • Unusual or rarely used JPEG features.
      • Deeply nested restart intervals.
    • When the application attempts to process this image, it consumes a disproportionate amount of CPU or memory, potentially exhausting server resources and making the application unavailable to legitimate users.
  • Mitigation Strategies:
    • Resource Limits:
      • Maximum Image Dimensions: Limit the maximum width and height of images that can be processed.
      • Maximum Decoding Time: Set a time limit for how long the application will spend decoding an image.
      • Memory Limits: Restrict the amount of memory that can be allocated for image processing.
    • Rate Limiting: Limit the number of image processing requests that can be handled within a given time period.
    • Monitoring: Continuously monitor resource usage (CPU, memory, network) to detect potential DoS attacks.