threat-modeling.md

Threat Model Analysis for apache/commons-lang

Threat: Deserialization of Untrusted Data

• Description: An attacker provides a malicious serialized object as input to the application. The application uses SerializationUtils.deserialize() to deserialize this data without any validation. The attacker crafts the serialized object to include a "gadget chain" – a sequence of class instantiations and method calls that, upon deserialization, ultimately lead to arbitrary code execution. This is a direct use of a Commons Lang function in a vulnerable way.
• Impact: Remote Code Execution (RCE), allowing the attacker to take complete control of the application and potentially the underlying server. Data theft, system modification, and further network compromise are all possible.
• Affected Component: SerializationUtils.deserialize()
• Risk Severity: Critical
• Mitigation Strategies:
  • Avoid Deserialization of Untrusted Data: The primary and most effective mitigation is to completely avoid deserializing data received from untrusted sources.
  • Whitelist-Based Deserialization: If deserialization of external data is absolutely necessary, implement a strict whitelist using Java's ObjectInputFilter. Configure the filter to allow only specific, known-safe classes to be deserialized. Reject all other classes. This is a crucial step.
  • Use Alternative Serialization Formats: Strongly consider using safer serialization formats like JSON or XML, combined with robust schema validation and secure parsing libraries. These formats are significantly less prone to arbitrary code execution vulnerabilities compared to Java serialization.
  • Keep Dependencies Updated: Regularly update all dependencies, including Commons Lang and any other libraries that might be part of a potential gadget chain. While the vulnerability is triggered by Commons Lang, other libraries can contribute to the exploit.

Threat: StringEscapeUtils Misuse Leading to Security Bypass (Filtered - Requires Careful Consideration)

• Description: While misuse of StringEscapeUtils is not a direct vulnerability within the library, it's included here (with a caveat) because it's a common and high-severity error directly related to a Commons Lang component. A developer incorrectly relies on StringEscapeUtils methods (like escapeHtml4(), escapeEcmaScript()) for security-critical input sanitization, believing they provide protection against XSS or SQL injection. An attacker crafts input that bypasses this incorrect escaping, leading to a successful injection attack. The core issue is the incorrect application of a Commons Lang function, leading to a bypass of intended security measures.
• Impact: Cross-Site Scripting (XSS) if misused for HTML escaping, SQL Injection if misused for SQL escaping, or other injection vulnerabilities depending on the specific context. This can result in data breaches, session hijacking, or defacement of the application.
• Affected Component: StringEscapeUtils (various escaping methods)
• Risk Severity: High
• Mitigation Strategies:
  • Use Dedicated Security Libraries: Never use StringEscapeUtils for security-critical input sanitization. Instead, employ specialized libraries and techniques designed for this purpose. For HTML, use a robust HTML templating engine (that handles escaping automatically) or a dedicated library like OWASP Java Encoder. For SQL, always use parameterized queries (prepared statements) or a well-vetted ORM that handles escaping correctly.
  • Developer Education: Thoroughly train developers on the proper use of escaping functions. Emphasize the crucial distinction between presentation-layer escaping (which StringEscapeUtils is suitable for) and security-critical input sanitization (which requires dedicated security mechanisms).
  • Code Reviews: Implement mandatory code reviews with a specific focus on identifying and correcting any misuse of StringEscapeUtils for security purposes. This is a critical preventative measure.