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SOAP API Pentesting

SOAP (Simple Object Access Protocol) APIs are widely used for communication between client and server applications. Pentesting SOAP APIs involves identifying vulnerabilities and assessing security risks associated with these interfaces. Here's an overview of SOAP API pentesting, common vulnerabilities, and useful resources:


  • Communication Protocol: SOAP APIs use XML-based messages to perform operations between client and server applications.
  • Formal Specification: SOAP APIs have a formal specification defining message structure, data types, and communication protocols.

Common Vulnerabilities

XML External Entity (XXE) Injection

  • XXE vulnerabilities occur when XML input is not properly validated, allowing attackers to include external entities that may disclose sensitive information or execute arbitrary code. Including an external entity in a SOAP request to read sensitive files on the server.

XML Injection

  • XML injection vulnerabilities arise when user-supplied XML input is not properly sanitized, leading to unexpected behavior or disclosure of sensitive information. Manipulating XML input parameters to modify SOAP request structure or execute unintended operations.

SOAPAction Header Injection

  • Manipulating the SOAPAction header can lead to unauthorized access, bypassing authentication, or triggering unintended operations on the server. Modifying the SOAPAction header value to execute administrative actions without proper authorization.

Insecure Deserialization

  • Insecure deserialization vulnerabilities can lead to remote code execution or unauthorized data access if attackers can manipulate serialized objects. Crafting malicious SOAP requests to exploit deserialization vulnerabilities in the server-side application.

Tools & Frameworks

  • Burp Suite: Widely used for intercepting and manipulating SOAP requests and responses, helpful for analyzing traffic and identifying vulnerabilities.
  • SoapUI: API testing tool specifically designed for testing SOAP and REST APIs, providing features for functional testing, security testing, and performance testing.
  • WS-Attacker: Burp Suite extension for testing Web Services security, including SOAP APIs, for vulnerabilities such as XML injection and XXE.


  • OWASP Web Services Security Project: Provides guidance and best practices for securing web services, including SOAP APIs, against common vulnerabilities.
  • W3C SOAP Specification: Official specification defining the SOAP protocol, message structure, and related standards.
  • Books: "Hacking Web Services" by Shreeraj Shah covers in-depth techniques for testing and securing web services, including SOAP APIs.