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Attack Tree Analysis for woltapp/blurhash

Objective: Degrade UX, Leak Image Info, or Cause DoS via BlurHash

Attack Tree Visualization

Goal: Degrade UX, Leak Image Info, or Cause DoS via BlurHash ├── 1. Degrade User Experience │ ├── 1.1. Provide Incorrect/Misleading BlurHashes │ │ ├── 1.1.1. Server-Side Manipulation (If server generates BlurHashes) │ │ │ └── 1.1.1.1. Compromise Server (General attack - OUT OF SCOPE, but necessary precursor) [CRITICAL] │ │ ├── 1.1.2. Client-Side Manipulation (If client generates BlurHashes) │ │ │ └── 1.1.2.2. Man-in-the-Middle (MitM) Attack [CRITICAL] │ └── 1.2. Cause Excessive Client-Side Processing [HIGH RISK] │ ├── 1.2.1. Provide Maliciously Crafted BlurHash String [HIGH RISK] │ │ └── 1.2.1.1. Use an extremely long BlurHash string. [HIGH RISK] │ │ └── 1.2.1.2 Use invalid characters in the BlurHash string. [HIGH RISK] │ │ └── 1.2.1.3. Craft a BlurHash string that triggers edge cases or vulnerabilities. │ │ └── 1.2.1.3.1 Exploit potential buffer overflows or integer overflows. [CRITICAL] │ └── 1.2.2 Provide BlurHash with very high component count (X and Y). [HIGH RISK] │ └── 1.2.2.1 Force client to allocate large memory. └── 3. Cause Denial-of-Service (DoS) ├── 3.1. Client-Side DoS [HIGH RISK] │ └── 3.1.1. Exploit 1.2.1.3 (Decoder Vulnerability) to crash the client. [CRITICAL] │ └── 3.1.2. Exploit 1.2.2.1 (High Component Count) to exhaust resources. [HIGH RISK] └── 3.2. Server-Side DoS (If server decodes BlurHashes) [HIGH RISK] ├── 3.2.1. Flood with maliciously crafted BlurHashes (similar to 1.2.1.3). [CRITICAL] └── 3.2.2 Flood with high component count BlurHashes (similar to 1.2.2.1). [HIGH RISK]

Attack Tree Path: 1.1.1.1. Compromise Server

  • Description: This is a general attack vector, not specific to BlurHash, but it's a necessary prerequisite for any server-side manipulation of BlurHash generation. The attacker gains unauthorized access to the server hosting the application.
  • Likelihood: Low (Depends on overall server security)
  • Impact: High (Full control over BlurHash generation, and potentially the entire application)
  • Effort: High
  • Skill Level: Advanced/Expert
  • Detection Difficulty: Medium/Hard (Depends on server monitoring and intrusion detection systems)
  • Mitigation: This is outside the scope of the BlurHash-specific threat model, but general server hardening, intrusion detection, and regular security audits are crucial.

Attack Tree Path: 1.1.2.2. Man-in-the-Middle (MitM) Attack

  • Description: The attacker intercepts the communication between the client and the server, allowing them to modify the BlurHash strings in transit. This requires breaking HTTPS, typically through certificate forgery or exploiting vulnerabilities in the TLS/SSL implementation.
  • Likelihood: Very Low (Requires breaking HTTPS)
  • Impact: Medium (Misleading placeholders for targeted users)
  • Effort: High
  • Skill Level: Advanced/Expert
  • Detection Difficulty: Hard (If HTTPS is properly implemented; otherwise, easier)
  • Mitigation: Ensure proper HTTPS implementation with valid certificates, certificate pinning (where appropriate), and up-to-date TLS/SSL libraries.

Attack Tree Path: 1.2.1.3.1. Exploit potential buffer overflows or integer overflows

  • Description: The attacker crafts a malicious BlurHash string that exploits a buffer overflow or integer overflow vulnerability in the decoding implementation. This could lead to arbitrary code execution or a denial-of-service (crash). This is the most critical vulnerability within the BlurHash library itself.
  • Likelihood: Very Low/Low (Requires a specific, undiscovered vulnerability)
  • Impact: High/Very High (Potential for remote code execution, application crash)
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Hard (Requires deep code analysis, fuzz testing, and potentially reverse engineering)
  • Mitigation: Rigorous code review, secure coding practices (safe string handling, bounds checking), extensive fuzz testing, and potentially static analysis tools.

Attack Tree Path: 3.1.1. Exploit 1.2.1.3 (Decoder Vulnerability) to crash the client

  • Description: This is the same vulnerability as 1.2.1.3.1, but specifically focusing on the client-side impact (DoS).
  • Likelihood, Impact, Effort, Skill Level, Detection Difficulty: Same as 1.2.1.3.1.
  • Mitigation: Same as 1.2.1.3.1.

Attack Tree Path: 3.2.1. Flood with maliciously crafted BlurHashes (similar to 1.2.1.3)

 *   **Description:** This is the same vulnerability as 1.2.1.3.1 and 3.1.1, but targeting the *server* if it decodes BlurHashes. The attacker sends a flood of requests containing malicious BlurHashes designed to trigger the vulnerability.
*   **Likelihood, Impact, Effort, Skill Level, Detection Difficulty:** Same as 1.2.1.3.1, but Impact may be higher due to server-wide DoS.
*   **Mitigation:** Same as 1.2.1.3.1, plus rate limiting and server-side input validation.

Attack Tree Path: 1.2. Cause Excessive Client-Side Processing

  • Description: The attacker provides BlurHash strings designed to consume excessive client-side resources, leading to slowdowns, freezes, or potentially crashes. This is primarily achieved through a lack of input validation.

Attack Tree Path: 1.2.1.1. Use an extremely long BlurHash string

    *   **Description:**  The attacker provides a BlurHash string that is significantly longer than expected.
    *   **Likelihood:** Medium (If no input validation)
    *   **Impact:** Low/Medium (Slowdown or temporary freeze)
    *   **Effort:** Very Low
    *   **Skill Level:** Novice
    *   **Detection Difficulty:** Easy (Input validation, performance monitoring)
    *   **Mitigation:**  Strictly limit the length of accepted BlurHash strings.

Attack Tree Path: 1.2.1.2. Use invalid characters in the BlurHash string

    *   **Description:** The attacker includes characters in the BlurHash string that are not part of the expected character set (likely Base83).
    *   **Likelihood:** Medium (If no input validation)
    *   **Impact:** Low (Likely to be rejected or cause an error)
    *   **Effort:** Very Low
    *   **Skill Level:** Novice
    *   **Detection Difficulty:** Very Easy (Input validation)
    *   **Mitigation:**  Enforce a strict character set for BlurHash strings.

Attack Tree Path: 1.2.2.1. Force client to allocate large memory (via high component count)

    *   **Description:** The attacker provides a BlurHash with an unusually high number of X and Y components, forcing the client to allocate a large amount of memory for decoding.
    *   **Likelihood:** Medium (If no input validation)
    *   **Impact:** Low/Medium (Slowdown or temporary freeze)
    *   **Effort:** Very Low
    *   **Skill Level:** Novice
    *   **Detection Difficulty:** Easy (Input validation, performance monitoring)
    *   **Mitigation:**  Impose reasonable limits on the X and Y component counts.

Attack Tree Path: 3.1. Client-Side DoS

  • Description: The attacker aims to make the client application unresponsive or crash it entirely.

Attack Tree Path: 3.1.2 (Exploit High Component Count)

This is the same as 1.2.2.1, but with a focus on the DoS outcome. Mitigation is the same: limit component counts.

Attack Tree Path: 3.2. Server-Side DoS

  • Description: The attacker aims to make the server unresponsive or crash it, impacting all users of the application. This applies if the server decodes BlurHashes.

Attack Tree Path: 3.2.2. Flood with high component count BlurHashes

    *   **Description:**  The attacker sends a large number of requests containing BlurHashes with very high component counts, overwhelming the server's resources.
    *   **Likelihood:** Medium (If no input validation or rate limiting)
    *   **Impact:** Medium/High (Server slowdown or resource exhaustion)
    *   **Effort:** Low
    *   **Skill Level:** Novice
    *   **Detection Difficulty:** Medium (Rate limiting, performance monitoring)
    *   **Mitigation:**  Implement strict input validation (limit component counts) *and* rate limiting on the server.