Hi there, For a detailed paper on cross-site scripting (and other injection practices) I would recommend the following paper: http://www.technicalinfo.net/papers/CSS.html It goes into alot of detail on the significance, what can/can't be done, a step through on a large site, and lots of options/methods on how to secure against the attacks. For context on alternative ways on encoding methods (to bypass many of the common "dangerous character" filters) that can be used in conjunction with cross-site scripting, read the following paper: http://www.technicalinfo.net/papers/URLEmbeddedAttacks.html Hope this all helps. RE: >>>>>>>>>>>>> In-Reply-To: <195f0718f5f1.18f5f1195f07at_private> http://www.idefense.com/idpapers/XSS.pdf http://www.cgisecurity.net/articles/xss-faq.shtml Those papers are by Endler and Zeno...they should get you informed. If you don’t feel like reading, I'll try to sum up the basic concepts for you and everybody else. In general there are two types of XSS attacks, transient and permanent. Lets say you have an E-commerce site named example.com. Example.com uses their own type of session cookie to maintain state when a customer makes transactions. An example of a transient attack would be if I knew bob currently has the example.com cookie on his system. If I sent an IM to bob with a link that was specially crafted w/ an XSS attack payload that sent bob’s example.com cookie to a cookie collecting script at bobs-evil-wife.com. So now bob’s wife can use his cookie to session hijack his example.com account and do what she pleases on bob’s account. Ok now lets say I have a message board, I want users to make colorful posts so I allow HTML to be put into posts, but I unfortunately I allowed everything including javascript. An Evil user comes along and inserts script into a post that when loaded, automatically posts "I am a luser" to every message board on the site, or it could do anything else the evil user wants to do on behalf of all the visitors that loaded the site up and were members of the board. Here are examples from this month of XSS attacks: http://online.securityfocus.com/archive/1/303226/2002-12-06/2002-12-12/0 http://online.securityfocus.com/archive/1/303542/2002-12-13/2002-12-19/0 http://online.securityfocus.com/archive/1/303545/2002-12-13/2002-12-19/0 Sadly this type of hole is extremly easy to find in any non-trival website...I've found hundreds all over major sites on the web. The developers just don't care much about them though because the second part of the attack, the user interaction, is difficult to accomplish. There has been much debate regarding if these types of vulns should be allowed on bugtraq. IMHO the disclosure of these types of attacks should be "moved" to webappsec list. Cheers, -Slow2Show- <-- graduating Friday woo hoo!! University of Florida >Can anyone explain to me or point me to a paper that explains exactly >what cross site scripting is, and how it could be useful/cause >problems for someone? Thanks. > >Mike _________________________________________ Webmail provided by Names.co Internet plc http://www.names.co.uk
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