Generate CSRF PoC
Last updated: December 6, 2021
Read time: 3 Minutes
To access this function, select a URL or HTTP request anywhere within Burp, and choose Generate CSRF PoC within Engagement tools in the context menu.
You can edit the request manually, and click the Regenerate button to regenerate the CSRF HTML based on the updated request.
You can test the effectiveness of the generated PoC in your browser, using the Test in browser button. When you select this option, Burp gives you a unique URL that you can paste into your browser (configured to use the current instance of Burp as its proxy). The resulting browser request is served by Burp with the currently displayed HTML, and you can then determine whether the PoC is effective by monitoring the resulting request(s) that are made through the Proxy.
Some points should be noted regarding CSRF techniques:
- Some requests have bodies (e.g. XML or JSON) that can only be generated using either a form with plain text encoding, or a cross-domain XHR. In the former case, the resulting request will include the header "Content-Type: text/plain". In the latter case, the request can include any Content-Type header, but will only qualify as a "simple" cross-domain request (and so avoid the need for a pre-flight request which typically breaks the attack) if the Content-Type header has one of the standard values that may be specified for normal HTML forms. In some cases, although the message body exactly matches that required for the attack request, the application may reject the request due to an unexpected Content-Type header. Such CSRF-like conditions might not be practically exploitable. Burp will display a warning in the CSRF PoC generator if this is liable to occur.
- If you manually select a CSRF technique that cannot be used to produce the required request, Burp will generate a best effort at a PoC and will display a warning.
- If the CSRF PoC generator is using plain text encoding, then the request body must contain an equals character in order for Burp to generate an HTML form which results in that exact body. If the original request does not contain an equals character, then you may be able to introduce one into a suitable position in the request, without affecting the server's processing of it.
CSRF PoC options
The following options are available:
- CSRF technique - This option lets you specify the type of CSRF technique to use in the HTML that generates the CSRF request. The Auto option is generally preferred, and causes Burp to select the most appropriate technique capable of generating the required request.