Then, consider how an attacker could use this vulnerability in conjunction with an XML flood attack using multiple documents to amplify the effect.

To analyze the likelihood of this attack, analyze the time taken by a regular XML document vs the time taken by a malformed version of that same document. When this happens, an attacker may exploit an asymmetric resource consumption attack to take advantage of the greater processing time to cause a Denial of Service (DoS). In certain scenarios, the amount of time required to process malformed documents may be greater than that required for well-formed documents. More Time Required ¶Ī malformed document may affect the consumption of Central Processing Unit (CPU) resources. In addition, use only well-formed documents and validate the contents of each element and attribute to process only valid values within predefined boundaries. The recommendation to avoid these vulnerabilities are to use an XML processor that follows W3C specifications and does not take significant additional time to process malformed documents. The document should not undergo any additional processing, and the application should display an error message. The XML parser should stop execution once detecting a fatal error. Multiple tactics will cause a malformed document: removing an ending tag, rearranging the order of elements into a nonsensical structure, introducing forbidden characters, and so on. When a document violates any of these principles, it must be considered a fatal error and the data it contains is considered malformed. The W3C XML specification defines a set of principles that XML documents must follow to be considered well formed.

Invalid XML Documents: vulnerabilities using documents that do not have the expected structure.

Malformed XML Documents: vulnerabilities using not well formed documents.

This cheat sheet exposes how to exploit the different possibilities in libraries and software divided in two sections: Even though we use XML schemas to define the security of XML documents, they can be used to perform a variety of attacks: file retrieval, server side request forgery, port scanning, or brute forcing. At the same time, these specifications provide the tools required to protect XML applications. Specifications for XML and XML schemas include multiple security flaws. XML Security Cheat Sheet ¶ Introduction ¶ Special Values: Infinity and Not a Number (NaN) Well-Formed Document to Well-Formed Document Normalized

Insecure Direct Object Reference Prevention

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