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Attack Tree Analysis for jakewharton/butterknife

Objective: Achieve Arbitrary Code Execution or Data Exfiltration via Butter Knife

Attack Tree Visualization

                                      Attacker's Goal:
                      Achieve Arbitrary Code Execution or Data Exfiltration
                                      via Butter Knife
                                                |
                      -----------------------------------------------------------------
                      |                                                               |
        1. Exploit Butter Knife's                                   2. Exploit Butter Knife's
           View Binding Mechanism                                     Resource Injection Mechanism
                      |                                                               |
        ------------------------------                            ------------------------------------
        |             |                                              |                  |
1.1  Reflection   1.2  Code                                     2.1  Reflection     2.2 Code Gen.
     Vulner-       Generation                                       Vulnerabilities    Vulnerabilities
     abilities     Vulnerabilities
        |             |                                              |                  |
  -------       -------                                        -------          -------
  |     |       |     |                                        |     |          |     |
1.1.1 1.1.2   1.2.1 1.2.2                                      2.1.1 2.1.2      2.2.1 2.2.2
!!!     !!!   !!!   !!!                                        !!!   !!!        !!!   !!!
(App-    (App- (Butter (Butter                                (App-    (App- (Butter (Butter
Specific)Specific) Knife)  Knife)                                 Specific)Specific) Knife)  Knife)
  |         |                                                              |         |
  |         |--- Implicit High-Risk Path 2 (See Below)                   |         |--- Implicit High-Risk Path 2 (Resource Variant - See Below)
  |
  |--- Implicit High-Risk Path 1 (See Below)

Attack Tree Path: 1.1.1 Reflection API Misuse Leading to Method Injection (View Binding)

  • Description: A theoretical vulnerability where a flaw in Butter Knife's reflection logic, combined with an application vulnerability that allows attacker control over class or method names used in reflection, could lead to arbitrary method calls.
  • Likelihood: Very Low
  • Impact: High (Arbitrary code execution)
  • Effort: High
  • Skill Level: Expert
  • Detection Difficulty: Hard

Attack Tree Path: 1.1.2 Class Loading Vulnerabilities (View Binding)

  • Description: Similar to 1.1.1, but involving the attacker influencing the class loading process during view binding. Requires a flaw in Butter Knife and an application vulnerability.
  • Likelihood: Very Low
  • Impact: High (Arbitrary code execution)
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 1.2.1 Template Injection in Generated Code (View Binding)

  • Description: A vulnerability within Butter Knife's annotation processor, where an attacker could inject malicious code into the generated binding classes.
  • Likelihood: Very Low
  • Impact: Very High (Arbitrary code execution)
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 1.2.2 Logic Errors in Generated Code (View Binding)

  • Description: A bug in Butter Knife's code generator that results in insecure or incorrect code, potentially creating exploitable vulnerabilities.
  • Likelihood: Low
  • Impact: Medium to High (Depends on the specific bug)
  • Effort: High
  • Skill Level: Advanced
  • Detection Difficulty: Hard

Attack Tree Path: 2.1.1 Reflection API Misuse Leading to Method Injection (Resource Injection)

  • Description: Analogous to 1.1.1, but related to resource injection (@BindString, @BindDrawable, etc.).
  • Likelihood: Very Low
  • Impact: High
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 2.1.2 Class Loading Vulnerabilities (Resource Injection)

  • Description: Analogous to 1.1.2, but related to resource injection.
  • Likelihood: Very Low
  • Impact: High
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 2.2.1 Template Injection in Generated Code (Resource Injection)

  • Description: Analogous to 1.2.1, but related to resource injection.
  • Likelihood: Very Low
  • Impact: Very High
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 2.2.2 Logic Errors in Generated Code (Resource Injection)

  • Description: Analogous to 1.2.2, but related to resource injection.
  • Likelihood: Low
  • Impact: Medium to High
  • Effort: High
  • Skill Level: Advanced
  • Detection Difficulty: Hard

Attack Tree Path: Implicit High-Risk Path 1: Application-Specific View ID Manipulation

  • Description: The application uses user-supplied or externally-sourced data to construct view IDs without proper validation or sanitization. This data is then used with Butter Knife's @BindView annotation. An attacker crafts malicious input that, when used as a view ID, allows them to influence the reflection process. This is not a direct Butter Knife vulnerability, but a vulnerability in how the application uses Butter Knife.
  • Example:
    • Vulnerable Code: @BindView(Integer.parseInt(userInput)) (If userInput is not properly validated)
    • Attacker Input: A carefully crafted string that, when parsed as an integer, somehow influences the reflection process (extremely difficult, but theoretically possible if there's a flaw in the interaction between the integer parsing and Butter Knife's internal logic).
  • Likelihood: Low to Medium (Depends entirely on the application's input handling)
  • Impact: High (Potential for arbitrary code execution, though difficult to achieve)
  • Effort: High
  • Skill Level: Advanced to Expert
  • Detection Difficulty: Medium to Hard (Requires careful code review and potentially dynamic analysis)
  • Mitigation:
    • Strict Input Validation: Ensure that all user input and data from external sources is rigorously validated and sanitized before being used in any way that could influence view IDs.
    • Use Static View IDs: Whenever possible, use statically defined view IDs (e.g., R.id.my_button) rather than dynamically constructing them.
    • Avoid Integer.parseInt with User Input for View IDs: This is a particularly risky pattern.

Attack Tree Path: Implicit High-Risk Path 2: Application-Specific Dynamic Class Loading with Butter Knife

  • Description: The application dynamically loads classes (e.g., from a remote server or based on user input) and then uses Butter Knife to bind views within those dynamically loaded classes. If the attacker can control the class loading process (e.g., by providing a malicious class), they can inject their own code. Butter Knife is then used to bind views within this malicious class, potentially triggering the execution of the attacker's code.
  • Likelihood: Low (Requires the application to have dynamic class loading and for the attacker to control it)
  • Impact: High (Arbitrary code execution)
  • Effort: High
  • Skill Level: Advanced to Expert
  • Detection Difficulty: Hard (Requires careful code review and potentially dynamic analysis)
  • Mitigation:
    • Avoid Dynamic Class Loading: If possible, avoid dynamic class loading altogether.
    • Strict Validation of Loaded Classes: If dynamic class loading is necessary, implement extremely strict validation of the loaded classes (e.g., code signing, checksum verification, sandboxing).
    • Isolate Dynamically Loaded Code: Use Android's security features (e.g., separate processes, limited permissions) to isolate dynamically loaded code and prevent it from accessing sensitive data or system resources.

Attack Tree Path: Implicit High-Risk Path 2 (Resource Variant): Application-Specific Resource ID Manipulation

  • Description: Similar to Implicit High-Risk Path 1, but the application uses user-supplied or externally-sourced data to construct resource IDs without proper validation. This data is then used with Butter Knife's resource binding annotations (e.g., @BindString, @BindDrawable).
  • Likelihood: Low to Medium
  • Impact: High (Potentially arbitrary code execution if combined with other vulnerabilities, otherwise likely a crash)
  • Effort: High
  • Skill Level: Advanced
  • Detection Difficulty: Medium to Hard
  • Mitigation: Same as Implicit High-Risk Path 1, but applied to resource IDs. Use static resource IDs whenever possible.