Extensible Markup Language (XML) Injection

XML injection is a type of security vulnerability that occurs when untrusted or malicious data is injected into an XML-based application or system, leading to unexpected behavior or unauthorized access. XML is a popular markup language used for storing and transmitting structured data.

In an XML injection attack, the attacker manipulates user-supplied input to inject malicious XML content into an XML document or input field. This can cause the application to misinterpret or execute the injected content, leading to various security implications.

The steps involved in an XML injection attack are as follows:

1. Identification of XML Input: The attacker identifies input fields or parameters in the application that interact with XML data, such as XML documents or XML-based APIs.
2. Construction of Malicious Input: The attacker crafts input data containing specially crafted XML tags, entities, or XPath expressions, aiming to manipulate the XML structure or exploit vulnerabilities in XML parsing and processing.
3. Injection Point: The attacker injects the malicious input into the vulnerable XML input field, causing the application to misinterpret or execute the injected XML content.
4. Unauthorized Actions: The injected XML content can lead to unauthorized actions, such as accessing sensitive data, modifying the XML structure, executing remote code, or even causing denial-of-service conditions.

To mitigate XML injection attacks, the following preventive measures can be implemented:

• Input Validation and Sanitization: Implement strict input validation and sanitization routines to filter out or escape any potentially malicious XML characters, tags, or entities.
• XML Parsers and Libraries: Use robust and well-tested XML parsers and libraries that follow secure coding practices to handle XML data safely, avoiding vulnerabilities related to XML parsing and processing.
• Least Privilege Principle: Ensure that XML-based components or services have limited privileges necessary for their intended tasks, minimizing the potential impact of a successful XML injection attack.
• Secure Configuration: Configure XML-related components or APIs securely, disabling features that may introduce vulnerabilities, such as external entity resolution or excessive entity expansion.