What is Broken Access Control?
Broken access control occurs when an application does not properly enforce user permissions, allowing unauthorized users to gain access to restricted resources. This can lead to data breaches and significant security vulnerabilities. One way to exploit broken access control is through XML injection, which targets applications that use XML for data interchange.
What is XML Injection?
XML injection is an attack technique that involves manipulating XML data sent to a web application. Attackers can exploit vulnerabilities in the XML parser to gain unauthorized access or execute malicious commands.
How XML Injection Works
Vulnerable XML Parser: The application uses an XML parser that is susceptible to manipulation.
Malicious XML Payload: The attacker crafts a malicious XML payload that alters the intended structure or data.
Unauthorized Access: The manipulated XML is processed by the application, allowing the attacker to access or manipulate sensitive information.
Example Scenario
Imagine an application that allows users to view their account information using XML requests. If the access control checks are not implemented correctly, an attacker could exploit this vulnerability.
XML Payload Example
xml
<user>
<id>1</id>
<action>view</action>
</user>
By injecting a different user ID, an attacker could access another user's account:
xml
<user>
<id>2</id> <!-- Changing ID to access another user's information -->
<action>view</action>
</user>
Data Exfiltration Example
If the application doesn't validate the user's access rights, the attacker might retrieve sensitive information, such as user credentials or personal data:
xml
<response>
<user>
<id>2</id>
<name>John Doe</name>
<email>john.doe@example.com</email>
</user>
</response>
YouTube Video:
This a video of mine exploiting BAC unprotected admin functionality Via XML code review :
Mitigation Strategies
To protect against broken access control via XML injection, developers should:
Implement Proper Access Control: Always verify user permissions before granting access to sensitive data.
Validate XML Input: Use strict schemas (e.g., XML Schema Definition - XSD) to validate incoming XML requests.
Use Secure Coding Practices: Follow best practices for secure coding, including input sanitization and output encoding.
Conclusion
Understanding broken access control through XML injection is critical for securing web applications. By recognizing these vulnerabilities and implementing robust security measures, developers can better protect sensitive information from unauthorized access.
Stay tuned for my upcoming video demonstrating a penetration test on this vulnerability!
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