attack-tree.md

Attack Tree Analysis for mingrammer/diagrams

Objective: To execute arbitrary code on the server hosting the application that uses mingrammer/diagrams.

Attack Tree Visualization

                                     +-------------------------------------------------+
                                     | Compromise Application Using mingrammer/diagrams |
                                     +-------------------------------------------------+
                                                     |
                                                     |
                                        +--------------------------+
                                        | Execute Arbitrary Code  |
                                        +--------------------------+
                                                     |
                                        +---------------------+
                                        | Input Validation    |
                                        | Vulnerabilities [!] |
                                        +---------------------+
                                                     |
                                        +======+======+
                                        |  1a  |  1b  |
                                        +======+======+
                                           [!]     [!]

Attack Tree Path: 1. Execute Arbitrary Code (Primary Goal)

1a. Input Validation Vulnerabilities (Diagram Definition) [Critical Node]: * Description: The application fails to properly sanitize or validate user-supplied input used to define the structure of the diagram (e.g., node names, connections, labels). This is the most direct and likely path to code execution. * Attack Scenario: * An attacker provides a crafted node label containing Python code. For example, if the application uses string formatting unsafely: f"Node('{user_input}')". If user_input is '); import os; os.system('rm -rf /'); print(' , this could lead to disastrous consequences. * Another example: using backticks within a node label if the application doesn't escape them properly: Node('whoami').
* Exploiting any form of template injection if the application uses a templating engine to generate the diagram definition and doesn't properly escape user input. * Likelihood: High (if input validation is weak or absent) / Medium (if some basic validation exists) * Impact: Very High (full server compromise, data loss, system destruction) * Effort: Low to Medium (depends on the complexity of the input validation bypass; simple string injection is low effort) * Skill Level: Intermediate (requires understanding of Python, web application vulnerabilities, and potentially string formatting/template injection techniques) * Detection Difficulty: Medium to Hard (might be detected by intrusion detection systems or code analysis, but can be obfuscated; well-crafted attacks might bypass simple filters) * Mitigation: * Strict Whitelisting: Allow only a predefined set of characters and patterns for all input fields. Reject anything that doesn't match. * Length Limits: Enforce strict length limits on all input fields. * Context-Aware Validation: Validate the data type of each input field (e.g., integer, string, specific format). * Avoid String Concatenation/Interpolation: Never build the diagram definition by directly concatenating user input with Python code. Use the diagrams library's API methods (Node(), Edge(), etc.) to construct the diagram programmatically. This is crucially important. * Input Sanitization Libraries: Use libraries like bleach (Python) to sanitize input and remove or escape potentially harmful characters. * Regular Expression Validation: Use regular expressions to enforce strict input formats. * Templating Engine (with Auto-Escaping): If using a templating engine, ensure it automatically escapes user input to prevent injection vulnerabilities.

Attack Tree Path: 1b. Input Validation Vulnerabilities (Diagram Attributes/Options) [Critical Node]:

• Description: Similar to 1a, but the vulnerability lies in the handling of user-controlled attributes or options passed to the diagrams library (e.g., graph_attr, node_attr, edge_attr). If these are not validated, they can be a vector for code injection.
  • Attack Scenario:
    • The application allows users to specify node colors or styles through a web form. An attacker injects malicious code into the color attribute, hoping it will be executed when the diagram is rendered.
    • If the application uses user input to construct the graph_attr dictionary directly, an attacker could inject arbitrary attributes that might be interpreted as code by the underlying rendering engine.
  • Likelihood: Medium (less common than direct code injection in the definition, but still a significant risk)
  • Impact: Very High (full server compromise)
  • Effort: Medium (requires understanding of the diagrams API and how attributes are processed)
  • Skill Level: Intermediate to Advanced (requires a deeper understanding of how diagrams interacts with the rendering engine)
  • Detection Difficulty: Medium to Hard (similar to 1a; requires careful analysis of how attributes are handled)
  • Mitigation:
    • Apply all the same mitigation techniques as described for 1a (whitelisting, length limits, context-aware validation, avoiding string concatenation, sanitization libraries, regular expressions, secure templating).
    • Specific Attribute Validation: Implement specific validation rules for each attribute, based on its expected data type and format. For example, a color attribute should be validated against a list of allowed colors or a specific color format (e.g., hex code).
    • Limit Attribute Control: Restrict the range of attributes that users can control. Avoid allowing users to set arbitrary attributes.