XXE with ChatGPT | Generate Custom XXE Payloads with AI

XXE (XML External Entity) is a type of vulnerability that allows attackers to inject malicious XML code into an application. The following ChatGPT prompts can make it easy to generate payloads for bug bounty and penetration testing.

1. Basic XXE

To get started, let’s start with a basic XXE payload customized for the particular XML structure used by the target web app.

Prompt:

Provide an example of a safe XXE payload that you can use for testing purposes for a blind XXE PoC that uses <burp collaborator> for the domain for the following .xml file and maintain the structure of the XML content:

<insert XML>

How it works:

1. The XML document declares a new entity called xxe that points to a resource on the Burp Collaborator server.
2. The document then references this entity in a child element.
3. When the application parses the document, it will attempt to fetch the resource, which can be used to detect XXE vulnerabilities.

2. SVG Image File XXE

SVG (Scalable Vector Graphics) files are XML-based vector image files that can also be vulnerable to XXE attacks, just like XML files.

Prompt:

Provide an example of a safe XXE payload that you can use for testing purposes for a blind XXE PoC that uses <burp collaborator> for the domain for the following .svg file and maintain the structure of the XML content:

<insert XML>

3. Excel File XXE

The newer Microsoft Excel .xlsx files can still be vulnerable to XXE attacks because they contain embedded XML files.

To modify the embedded XML file:

1. Extract the contents of the .xlsx file.
2. Edit the XML file in a text editor using the ChatGPT prompt.
3. Re-zip the contents.
4. Rename the .zip file back to .xlsx.

Prompt:

Provide an example of a safe XXE payload that you can use for testing purposes for a blind XXE PoC that uses <burp collaborator> for the domain for the following sharedStrings.xml extracted from a .xlsx file and maintains the structure of the XML content:

<insert XML>