Re: Is your web application really secure? ("CSRF")

I've thought for a while now that browsers probably shouldn't allow POST requests for another domain (especially scripted ones). Unfortunately that would break lots and lots of web applications so the chances of it being implemented are somewhere around zero.

One thing that might help a bit is to set up your webserver to prohibit POSTs that don't have a referer header from your trusted site(s). I'm pretty sure there's a way to do that in apache.

As far as I know ~~you~~ a malicious site can't fake a referer header* (unless maybe if you allow cross-site XMLHTTP - but all modern browsers prohibit that - right?)

Good suggestion on the tokens, by the way.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Comment on Re: Is your web application really secure? ("CSRF")

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Re^2: Is your web application really secure? ("CSRF") by betterworld (Curate) on Mar 27, 2007 at 19:31 UTC
I've thought for a while now that browsers probably shouldn't allow POST requests for another domain (especially scripted ones). Unfortunately that would break lots and lots of web applications A good start would be to warn the user that the form is sent to an external site, and not to send cookies.	[reply]
Re^2: Is your web application really secure? ("CSRF") by MidLifeXis (Monsignor) on Mar 29, 2007 at 17:26 UTC
As far as I know you a malicious site can't fake a referer header* (unless maybe if you allow cross-site XMLHTTP - but all modern browsers prohibit that - right?) Never trust the browser --MidLifeXis	[reply]
Re^3: Is your web application really secure? ("CSRF") by Joost (Canon) on Mar 29, 2007 at 19:25 UTC
Yes, but I was talking about malicious sites faking referers without the user's explicit permission. If a user wants to forge a referer header there's no way to stop it. Note that we're trying to protect the user, not the web app per se. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]


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