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AEM Forms - CSRF Token Verification

James_R_Green

24-10-2018

Hi,

I am interested in how the CSRF protection works in AEM Forms when submitting to a REST endpoint (custom sling servlet deployed to AEM).

I see that there is a ":cq_csrf_token" inserted when my form is submitted and I can see it is passed in the request.

1) Is this token automatically verified by AEM when POSTing to a rest endpoint - if so, how does it achieve this?

2) If this is not automatically verified what code would be needed within my rest endpoint in order to validate the csrf token is legitimate?

I have searched for this information but cannot find all of the details, can someone  point me in the right direction?

Thanks,

Jim

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James_R_Green

25-10-2018

Hi,

If I tamper with the CSRF token in the browser inspector, I get an error which suggests the token is verified automatically (option 1 in my original post). I can see from the error this happens here:

guideContainer.af.internalsubmit.jsp HTTP/1.1] com.adobe.granite.csrf.impl.CSRFFilter doFilter: the provided CSRF token is invalid

guideContainer.af.internalsubmit.jsp HTTP/1.1] com.adobe.granite.csrf.impl.CSRFFilter isValidRequest: not well formed CSRF token - rejecting

Where is the code for internalsubmit.jsp? I cannot find it anywhere!

Thanks,

Jim

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smacdonald2008

26-10-2018

James - we asked the Forms team to respond to this question.

I know in Sites AEM - when you want to invoke a Sling Servlet - you use the AEM JQuery version. It includes a CSRF token.

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sudhanshu_singh

19-11-2018

Hi James,

The CSRF handling for Forms is quite similar, and the CSRF clientLib part of the forms runtime is responsible for passing the required token on submission. This token is validated as part of the CSRFFilter which you are seeing in the logs you shared.

Thanks & Regards,

-Sudhanshu