threat-modeling.md

Threat Model Analysis for doctrine/lexer

Threat: Resource Exhaustion via Malicious Input

• Description: An attacker sends specially crafted input strings to the application that are designed to be computationally expensive for the lexer to process. This could involve deeply nested structures or extremely long tokens that exploit inefficiencies in the lexer's tokenization or parsing logic. The attacker aims to overload the server's CPU or memory by forcing the lexer to consume excessive resources, leading to a Denial of Service.
• Impact: Application slowdown, service unavailability, server crash.
• Affected Lexer Component: Tokenizer module, potentially core parsing logic.
• Risk Severity: High
• Mitigation Strategies:
  • Implement input validation and sanitization before passing data to the lexer. Limit input size and complexity based on expected use cases.
  • Set timeouts for lexer execution to prevent unbounded processing of overly complex inputs.
  • Monitor server resource usage (CPU, memory) and implement rate limiting if necessary to protect against sudden spikes in lexer processing demands.
  • Regularly update doctrine/lexer to benefit from performance improvements and bug fixes that may address potential resource consumption issues.

Threat: Incorrect Tokenization leading to Logic Errors

• Description: An attacker crafts input that exploits edge cases, bugs, or ambiguities in the lexer's grammar or parsing logic. This causes the lexer to produce incorrect tokens, misinterpreting the input's intended structure. The application, relying on these incorrect tokens, then executes unintended logic, potentially leading to security vulnerabilities, data corruption, or application malfunction. This is especially critical if the application uses the lexer to parse security-sensitive data or control critical application flows.
• Impact: Application malfunction, incorrect data processing, potential security vulnerabilities depending on application logic, data corruption.
• Affected Lexer Component: Tokenizer module, parsing logic, grammar definition.
• Risk Severity: High
• Mitigation Strategies:
  • Thoroughly test the application's input handling with a wide range of valid and invalid inputs, including potentially malicious examples specifically designed to exploit known or potential lexer edge cases and grammar ambiguities.
  • Carefully review and validate the application logic that processes tokens generated by the lexer. Design the application to be resilient to unexpected token sequences or potentially incorrect tokenization. Implement robust error handling and validation of token streams within the application logic.
  • Regularly update doctrine/lexer to benefit from bug fixes and improvements in parsing accuracy that address potential vulnerabilities leading to incorrect tokenization. Consider contributing test cases to the doctrine/lexer project to improve its robustness against malicious inputs.