The processes for the attack using the execution of scripts in the victim's browser are very similar to example 1, however, in this case, the Session ID does not appear as an argument of the URL, but inside of the cookie. Including the parameter Set-Cookie in the HTTP header response, the attacker is able to insert the value of Session ID in the cookie and sends it to the victim's browser. This method explores the server response to fix the Session ID in the victim's browser. The attack using this method becomes much more efficient because it's impossible to disable the processing of these tags in the browsers. Tag also is considered a code injection attack, however, different from the XSS attack where undesirable scripts can be disabled, or the execution can be denied. Using the function okie, the browser which executes the command becomes capable of fixing values inside of the cookie that it will use to keep a session between the client and the Web Application. In this case, the aggressor could use attacks of code injection as the XSS (Cross-site scripting) attack to insert a malicious code in the hyperlink sent to the victim and fix a Session ID in its cookie. Most browsers support the execution of client-side scripting. The form could be hosted in the evil web server or directly in html formatted e-mail. Session token in a hidden form field:In this method, the victim must be tricked to authenticate in the target Web Server, using a login form developed for the attacker.Session token in the URL argument: The Session ID is sent to the victim in a hyperlink and the victim accesses the site through the malicious URL.Below are some of the most common techniques: There are several techniques to execute the attack it depends on how the Web application deals with session tokens. Instead, the Session Fixation attack fixes an established session on the victim's browser, so the attack starts before the user logs in. There is no way for the server to check in the HTTP request that this cookie is HttpOnly (or the path) so this flag won't stop this attack occurring.The session fixation attack is a class of Session Hijacking, which steals the established session between the client and the Web Server after the user logs in. As your cookie is set in JavaScript, this would override the HttpOnly flag because of the more specific path. Setting HttpOnly cookies would prevent cookies being stolen but if the XSS vulnerability exists it means that other vulnerabilities are likely such as the one described in your scenario. This should stop JavaScript code from being entered as the protocol will be http/ https and not javascript in the cancel link: CancelĬancel URL will also have to be correctly HTML encoded to prevent break-out of the href attribute value context. check that it begins with or Anything that does not match should be rejected and an alert flagged to them. They should be validating that Cancel URL is a valid HTTP absolute URL. I would have thought if mtgox set their cookies to be http only then that would stop this from occurring? Perform any actions on behalf of his account - "Session riding". As soon as user signs in you can use fixated SID to Your server script should run cron task every 5 minutes, checking if SID is Someday user logs in, and his session will stay the same SID. It's called Cookie tossing, and our cookie shadows original SESSION_IDīecause more specific Path-s are sent first.ĭokie="SESSION_ID=SID Domain=. Path=/code" Get some guest SID with server side and fixate it using this XSS. User is supposed to wait 5 seconds until setTimeout in JS assigns location to our javascript: URL. MtGox has X-Frame-Options so it won't work in Put your payload in window.name and redirect to "=cancel" Name='okie="SESSION_ID=SID Domain=. Ĭreate Checkout button and set Cancel URL to javascript:eval(name) I discovered session fixation leading to account takeover. I am trying to understand this session fixation attack that was described in theory against mtgox (a well known bitcoin exchange):
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