On 03/10/2010 07:44 PM, Caleb James DeLisle wrote: > 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.
Sammy also required that XSS is enabled. Protecting from attacks originating in the wiki is kind of impossible at the moment, since JS can be inserted anywhere, and there's no (nice) way to prevent attacks from JS inside the application. As long as JS can be inserted, an attacker can do all the steps that the client would do to perform an action. The secret token works as a prevention mechanism when the attack comes from another site because the browser security model prevents the attack code to read the form. > > 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 >>> >> _______________________________________________ >> devs mailing list >> [email protected] >> http://lists.xwiki.org/mailman/listinfo/devs >> > > _______________________________________________ > devs mailing list > [email protected] > http://lists.xwiki.org/mailman/listinfo/devs > -- Sergiu Dumitriu http://purl.org/net/sergiu/ _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
