W3C home > Mailing lists > Public > public-web-security@w3.org > February 2013

Re: CORS question

From: John Wilander <john.wilander@owasp.org>
Date: Wed, 6 Feb 2013 07:51:34 +0100
Message-Id: <CD72DDFB-1D99-4337-A174-4CC53F2A2725@owasp.org>
Cc: Brandon Sterne <brandon@hackmill.com>, "public-web-security@w3.org" <public-web-security@w3.org>
To: "Hill, Brad" <bhill@paypal-inc.com>
I would argue that CSRF has become more convenient with CORS. The attacker previously had to open invisible iframes with tailored forms for each HTTP POST he/she wanted to send. Now the attacker can just parameterize and send it via Ajax.

Do you agree? Or am I missing a more convenient CSRF POST method for legacy browsers?

   Regards, John

My music http://www.johnwilander.com
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5 feb 2013 kl. 23:37 skrev "Hill, Brad" <bhill@paypal-inc.com>:

> Brandon,
> The requirement is that CORS does not introduce any new Cross-Site Request Forgery attack capabilities not present in legacy user agents.  Therefore, all requests  that cannot be generated by pre-CORS user agents through methods like GET, POST and HEAD that are available through legacy HTML+JS must be anonymous or pre-authorized.
> The user agent should not send requests with credentials on non-simple HTTP methods unless and until the server indicates it is prepared to accept such by responding to the pre-flight request.
> Does this answer your question?
> -Brad
> From: brandon.sterne@gmail.com [mailto:brandon.sterne@gmail.com] On Behalf Of Brandon Sterne
> Sent: Tuesday, February 05, 2013 1:38 PM
> To: public-web-security@w3.org
> Subject: CORS question
> Hey guys,
> Co-workers of mine were trying to understand the treat model of CORS, and I was having trouble articulating some of the particular risks that the spec attempts to avoid.  Why does the OPTIONS pre-flight request never carry credentials?
> Thanks,
> Brandon
Received on Wednesday, 6 February 2013 06:52:03 UTC

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