Take a look at the "sammy is my hero" worm, myspace sent a hash to the user 
like the one you propose,
the worm made the required get request to get the hash, then made the post 
along with the hash.
What prevents javascript from opening the page with the hash in an iframe and 
then reading in the iframe
to get the hash, then creating a form with the required data and posting it to 
the save action?

If we were to combine a requirement for post requests with checking of the 
referrer header, then we
would block links, forms and javascript based attacks leaving only an attack 
through older versions
of flash which support referrer forgery and at this point the difficulty of the 
attack becomes such that
we need to consider a wider array of attack vectors.


Caleb


Alex Busenius wrote:
> Unfortunately, using POST requests instead of GET requests is not
> enough. It will not prevent attacks that use forms and/or JavaScript to
> generate POST requests.
> 
> Alex
> 
> 
> On 03/09/2010 02:48 PM, Caleb James DeLisle wrote:
>> I had thought about proposing this myself but decided against it because it 
>> seems
>> to me like a workaround for problems which can be solved in other ways.
>>
>> Suppose we were to add a check to the actions which alter data which made 
>> sure the request method
>> was 'post' and made it configurable in one of the configuration files? We 
>> would have
>> to look over the default skins for incorrect links and leave the 
>> configuration
>> option off by default for backward compatibility at least until the next 
>> major version
>> but we could provide wiki operators the ability to prevent CSRF.
>>
>> Caleb
>>
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