I have been investigating this for some time, but I haven't found anything to satisfy my curiosity. Is it possible, as a user, to be the victim of a CSRF attack if cookies are disabled. Obviously CSRF depends on the users browser to send the user's credentials with the forged request to the legitimate server. Besides IP addresses, browsers don't automatically send in any other session values do they? In that case, as long as a user can login with cookies disabled, they would be safe from CSRF even on vulnerable websites.
So, you have to ask yourself how does the server know one client from another? In majority of cases, it is the session cookie, but there are other ways as well.
Consider an admin application, that is configured to work only if accessed from localhost. Here, the server is trusting the IP Address of the browser. Now, if an attacker creates a page like <img src="http://localhost/do/something/harmful"/>, and somehow gets the administrator to visit his page, you have a CSRF.
Other examples include abusing Http basic and digest authentication, as Bruno already pointed out.
There are other forms of authentication supported by browsers, in particular HTTP Basic and HTTP Digest, as well as SSL/TLS client-certificates. Unfortunately, the interface to "log out" when using these mechanisms is usually fairly poor. Unlike cookies and forms, stopping to use the credentials is controlled by the browser (not by the server and its cookies), but the buttons are at best in some advanced menu in general (if they exist at all).
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I have ASP.NET MVC app that uses Forms Authentication. After user is authenticated, in response he will receive forms cookie that contains auth information. Now regarding the forms cookie: It is encrypted by a machine key and it is protected from tampering by signature. I also use HTTPS... However, what if somehow I get the cookie and try to make request from another client (meaning that the request will be made from another IP address)?
It seems to me that this scenario will work. Are there any ways to defend from this kind of attack?
If you are using HTTPS everywhere on your site and set requireSSL="true" on your system.web/authentication/forms element in web.config, you are instructing the browser to only pass that cookie back over an HTTPS connection. This will protect against the vast majority of traffic sniffing-based session hijacking attacks and you should definitely use it if your site is HTTPS only.
Forms Authentication is inherently stateless. The server is encrypting the following information and storing it client-side: CookiePath, Expiration, Expired, IsPersistent, IssueDate, Name, UserData, Version. Assuming your machineKey hasn't been compromised, the client will just see this as a blob of encrypted data. When it presents that blob to the server again, the server decrypts it and converts it back into a FormsAuthenticationTicket, validates the fields in the ticket against config, verifies that the ticket isn't expired, etc. and decides whether to treat the request as authenticated. It doesn't 'remember' anything about which tickets are outstanding. Also note that it doesn't include the IP address anywhere.
The only real attack vector I can think of if you are HTTPS-only, take care to protect your machineKey, and set the forms auth cookie to requireSSL would be for an attacker to target the client's browser and/or computer. Theoretically they could steal the cookie from memory or disk out of the browser's space. It might be possible for a virus/trojan to do this or even a malicious browser extension. In short, if a user could get their hands on a valid, non-expired Forms Auth cookie, they could present it from any machine they wanted to until it expired. You can reduce the risk here by not allowing persistent auth cookies and keeping your timeouts to a minimum.
If they had the machineKey, they could create FormsAuth cookies from scratch whenever they wanted to.
Oh.. Can't forget Heartbleed. If you had a load balancer or reverse proxy that was using an insecure version of OpenSSL, it's possible an attacker could compromise your private key and intercept traffic over HTTPS connections. ASP.NET doesn't use OpenSSL, so you're safe from this in a pure-MS stack. If you ever hear anything about a vulnerability in MS' SSL implementation, you'd want to patch it ASAP and get your passwords changed and certificates re-issued.
If you are concerned about the browser/machine based hijacking, you might want to take a look at a project I started [and abandoned] called Sholo.Web.Security (https://github.com/scottt732/SholoWebSecurity). It's goal was to strengthen Forms Authentication by maintaining state on the server at the expense of some overhead on each request. You get the ability to do things like revoke tickets server-side (kick/logout a user) and prevent users from moving tickets between IP addresses. It can get annoying in the traveling mobile user scenario that Wiktor describes (it's optional). Feel free to fork it or submit pull requests.
The Anti-CSRF features that 0leg refers to apply to the UI/form mechanism that initiates the login process, but to my knowledge there is nothing in the Forms Authentication process itself that relates to CSRF. That is, once the cookie is issued to the client, the only thing protecting it from being bounced between servers is the fact that cookies are restricted to the domains/subdomain they were issued for. Your stackoverflow.com cookies won't be presented to serverfault.com. The browser takes care of that stuff for you.
Are there any ways to defend from that kind of attacks?
You shouldn't. Years ago we have had implemented such feature and abandoned it soon. It turned out that:
a single user making requests from the very same browser/machine but switching between http/https can sometimes be seen from different IP adresses
a single user traveling and using her mobile phone sometimes makes consecutive requests from different IP addresses when her phone switches between BTSes
Just to clarify the terminology, session hijacking is usually referred to the vulnerability where an unauthorized user accesses the session state on the server.
Authentication cookies are different from session cookies. ASP.NET puts a great deal more precautions in safeguarding authentication cookies. What you describe is better described by the term CSRF (Cross Site Request Forgery). As #Wiktor indicated in his response, restricting access by IP is not practical. Plus, if you read how CSRF works, the exploit can run in the user browser from the original IP address.
The good news is that ASP.NET MVC has built in support for CSRF prevention that is pretty easy to implement. Read here.
For username/pwd verification - the good websites use https - to avoid sending cleartext password over the wire. If I have a site where I want to do this - i.e. login over https. However - after logging in the rest of the stuff should be over http. Is this possible - if yes, why don't we see too many websites doing this. If not, why not?
You might want to read up on Firesheep. The short form is that this technique allows malicious people to hijack the session.
if yes, why don't we see too many websites doing this
The usual excuse for not using end-to-end TLS/SSL is that it causes the web app to take a performance hit, slow response times etc. This is a very flawed argument for https-sometimes security policy. Not entirely unfounded, but still unjustifiable.
If not, why not?
The thinking is that the only inherently vulnerable aspect of user access control is the authentication phase, i.e. where you supply your username and password to prove you are who you say you are. Organizations are aware of the risk of transmitting the credentials in clear text. After this process however, authorization is carried out server side and the web app trusts you from there on out and there are no credentials to protect any more.
Or are there?
As jszakmeister pointed out very succinctly, the session cookie is every bit as security critical as a username/password pair. Should someone get a hold of that, they might as well have seen the password and username on post-it.
I've tried searching and found questions that were close to this, but I could not find one answer that actually details this exact issue.
What (if anything) prevents a user from sniffing a network, getting all the asp.net forms authentication cookies a site is sending to me (or sniff the cookies I'm sendint to the server), setting those cookies in their own browser and viewing the site as the authenticated user?
Inherently, I don't think there's any native mechanism to prevent the scenario you describe. I think that's one reason MS recommends that Forms Authentication cookies have a very limited lifespan (set a short Expiration time), and be communicated across SSL.
SSL is the only thing that can prevent it.
I'm writing a mostly ajax-driven web application and I'm looking at how to protect the user from CSRF attacks. I'm planning to run the pages of the application where the user is logged in to do his work in HTTPS mode.
Does running the page on HTTPS work to protect against CSRF attacks?
No, running a page on HTTPS does not protect it from CSRF. The fact that the communications between the browser and server is encrypted has no bearing on CSRF.
I suggest reading the OWASP guidance on preventing CSRF.
A general, golden rule woule be:
Never trust that the incoming client request is a legitimate one. Be always suspicious and assume that the request could be maliciously forged.
Few specific rules beyond the mentioned OWASP article:
if your data needs authentication/authorization, avoid generic interfaces on the server, like the CRUD interface. easy to code, difficult to authorize specific requests coming from clients. instead, offer a SOA-style interface with explicit methods dedicated to specific use cases where you will have direct control over requests and their parameters.
http://msdn.microsoft.com/en-us/library/ms954638.aspx
even if the framework provides some control over the request validity (ASP.NET viewstate), check again if the user is authorized to pass the set of incoming parameters.
I'll try to explain:
• HTTPS prevents from someone on the same network to get your Session KEY/ID. Say they got your session identification key/id, then they can fake your IP if needed and send all POST requests they want back to server.
With HTTPS all HTTP body (the whole "HTML") is encrypted. Hence no session key is being guessed.
• What happens in CSRF is that the user is clicks a link, which also creates a request to another server and communicates with it, say using user's session but NOT ON THE SAME NETWORK. Means that it cannot listen to what the server replies back to user. If the attacker knows the replies and can communicate them, voila. No problem. No money's left on the user account. But if the server sends a random token to the IP associated with the session, then the attacker cannot guess it on a different network!
The best possible solution is to include secret tokens - to identify the user - in form submissions to the server. Refer to the following links for more information.
http://en.wikipedia.org/wiki/Cross-site_request_forgery
https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)
http://www.codinghorror.com/blog/2008/10/preventing-csrf-and-xsrf-attacks.html
http://seclab.stanford.edu/websec/csrf/
https doesn't safeguard your app from xss attacks. You need csrf token which should be (1) encrypted (2) expiring after some time (3) CSRF token based on page & time
Is there any way (apart from HTTP authentication, which I gather is inherently insecure over the Internet?) for a "real life" website to handle logins and authentication rather than the traditional way, using session cookies?
HTTP digest authentication (which is quite a different beast from HTTP basic authentication) is quite secure over straight HTTP, and not at all difficult to implement on the server. Nothing is sent over the wire that could reveal what the password is, just information that allows the client to demonstrate to the server that they have the correct password.
If you want a decent explanation of how to implement HTTP digest authentication in your application, Paul James has an excellent article on it.
The only real problem with HTTP authentication is in the browsers themselves: the UI is terrible, but that can be overcome with some Javascript.
Addendum: This answer is almost a decade old. These days, you should really be using HTTPS regardless of any other considerations.
HTTP basic authentication is perfectly safe when used with a SSL (https://) website since all HTTP traffic including the credentials will be encrypted. One subjective drawback though is when using this method your users will need to interact with their browser's authentication popup in order to log in to your site.
To be clear, the only REAL way to do this is through HTTPS.
But, since I assume this is not an option, and I also assume you are looking for a "fully managed login" system, I continue:
Other than HTTPS it is possible to use JavaScript to do secure hashing of passwords on the client side, to prevent revealing plain text passwords over-the-wire, but this is only a half-solution.
The problems with this approach are:
A replay attack is still a viable option.
Only users with JavaScript enabled would be able to auth in this way.
Another approach is a more complicated challenge / response mechanism:
Send a "Challenge" along with the login page.
Calculate the hash of the Password + Challenge client side.
Submit the login.
Calculate the hash of the Password + Challenge (which MUST NOT be trusted in the page request) on the server side, and compare.
And the problems with that:
Only users with JavaScript enabled would be able to auth in this way.
The PLAINTEXT password must be stored on the server to validate the challenge response, and must be encrypted on disk or otherwise protected.
Now, to be fair, problem #2 is not as big of a danger as it sounds. In fact when you instead use HASH authentication, the hash itself is raised to the level of "key".
At this point it is fairly secure to use a cookie to store a randomly generated login ReferrenceID, similar to their session ID, but the server may want to encrypt using the referring IP as part of the IV or KEY to prevent other users from Hijacking the ReferrenceID.
Anyways, I hope that provides a little bit of direction in the way of your design.
HTTP authentication is not insecure when using HTTPs.
Firstly, HTTP Auth is secure over SSL other than the fact that you can't implement a true "Logout" functionality. User need to close their browser, which is pretty bad.
Secondly, It you need to use HTTPS in all cases to make it secure, after that you got Basic Auth similar stuff such as "Digest" and "NTLM Auth".
When you're using https, you can also install a certificate in your client's browser and verify that. myopenid offers this for their OpenID accounts. I have one and it works really well (from the client-side point of view).
Using SSL for encryption in combination with HttpOnly Cookies to help prevent XSS is your best bet for using cookies. I'm not going to say it is bullet-proof, though.