How do websites generally log users out and send them to the log in screen automatically when a user's session expires? Is this done through ajax or running async handlers? Can you give me a bit of an explanation.
Banks and such use a client-side timeout via javascript, or something similar. Really, though, the server handles the actual session, so if you disabled the client-side logic it would act as if you were attempting to make transactions while logged out.
Use a cookie as well as a session.
Cookie must be set when a session is
started.
If the cookie is present but the
session is gone, redirect to the
login screen.
If there is no session and no cookie
do nothing
(pardon me if you can't do that because I never used ASP and basing my answer on my PHP knowledge)
Typically, you set an expiration timestamp on your session ID cookie. When the cookie fails to be sent, the client is logged off (no given session ID).
This method is often combined with JavaScript and another timestamp token. When the timers start running down, a notification is sent that allows the user to "refresh" their session... essentially, making a request before the session timestamp expires.
The "refresh" request could be anything, even something as simple as an image load.
If you are using Tomcat you can use its built in <security-constraint> mechanism within your web.xml definition. All of the timing, login screen, and page redirects are handled by Tomcat with little effort on your part other than definitions.
Oh, IIS... nevermind.
Related
Background: I have a javaee webapp deployed on tomcat which uses form based authentication. When the web server receives a login request, it sends the request to a dedicated authentication service which validates user login (User id and password). After successful authentication user's session is maintained in the web server.
Problem: I have written a simple webpp source code here, to simulate the scenario. On successful login the current HttpSession instance is invalidated and new instance is created. For each request for a post login page, the session is validated. A new JSESSIONID cookie is set which is used to identify the user during the session until session is expired or user logs out. This cookie can easily viewed in browser's dev tools. If I copy the cookie and set this in a different browser via JavaScript (document.cookie="JSESSIONID=xyzz") and then try to access a post login page, the server identifies it as a valid request and session is validated successfully. The post login page is served without user being challenged for user Id and password.
POC: User opens chrome and enter the URL http://localhost:8080/mywebapp/ and logs in with admin and pass1234. On successful log in the home page http://localhost:8080/mywebapp/home is shown. Now the JSESSIONID cookie is copied and set in FireFox. User enters http://localhost:8080/mywebapp/home in Firefox and is shown the home page without being challenged for userId and password.
Question: How can this be prevented wherein same session is getting replicated over multiple browsers?
You can't prevent this specific case of simply copying the cookie from your own browser (or by copying the cookie value from a HTTP payload copypaste/screenshot posted by an ignorant somewhere on the Internet). You can at most prevent the cookie getting hijacked by XSS or man-in-middle attacks.
This all is elaborated in Wikipedia page on the subject Session Hijacking of which I snipped away irrelevant parts (either already enforced by Servlet API, or are simply not applicable here).
Prevention
Methods to prevent session hijacking include:
Encryption of the data traffic passed between the parties by using SSL/TLS; in particular the session key (though ideally all traffic for the entire session[11]). This technique is widely relied-upon by web-based banks and other e-commerce services, because it completely prevents sniffing-style attacks. However, it could still be possible to perform some other kind of session hijack. In response, scientists from the Radboud University Nijmegen proposed in 2013 a way to prevent session hijacking by correlating the application session with the SSL/TLS credentials[12]
(snip, not relevant)
(snip, not relevant)
Some services make secondary checks against the identity of the user. For example, a web server could check with each request made that the IP address of the user matched the one last used during that session. This does not prevent attacks by somebody who shares the same IP address, however, and could be frustrating for users whose IP address is liable to change during a browsing session.
Alternatively, some services will change the value of the cookie with each and every request. This dramatically reduces the window in which an attacker can operate and makes it easy to identify whether an attack has taken place, but can cause other technical problems (for example, two legitimate, closely timed requests from the same client can lead to a token check error on the server).
(snip, not relevant)
In other words:
Use HTTPS instead of HTTP to prevent man-in-middle attacks.
Add a checkbox "Lock my IP" to login form and reject requests from different IP associated with same session in a servlet filter. This only works on users who know themselves they have a fixed IP.
Change session cookie on every request. Interesting at first sight, but breaks when user has same website open in multiple browser tabs/windows in same "session".
Not mentioned, but make sure you don't have a XSS hole anywhere, else it's very easy stealing cookies.
Last but not least, I'd like to make clear that this problem is absolutely not specifically related to Servlet API and the JSESSIONID cookie. All other stateful server side languages/frameworks such as PHP (PHPSESSID) and ASP (ASPSESSIONID) also expose exactly the same security problem. The JSESSIONID was previously (decade ago orso) only a bit more in news because by default it was possible to pass the session identifier along in the URL (which was done to support HTTP session in clients who have cookies disabled). Trouble started when ignorant endusers copypasted the full URL with JSESSIONID inside to share links with others. Since Servlet 3.0 you can turn off JSESSIONID in URLs by enforcing a cookie-only policy.
<session-config>
<tracking-mode>COOKIE</tracking-mode>
</session-config>
See also:
How do servlets work? Instantiation, sessions, shared variables and multithreading
How to prevent adding jsessionid at the end of redirected url
remove jsessionid in url rewrite in spring mvc
What you have stated is called session hijacking. There are many good answers on how to prevent it.
Using same Jsession ID to login into other machine
we can use Encryption or hide JSESSIONID using Browser control.
Thanks
I can redirect a user to home page upon session logout.. this was very simple. However, if an user had logged into the app and had the page open, even on session time out, he is able to perform all the functions(this is bad).
The redirect does not happen until the page is refreshed, or submitted to the server... there are some update functions that could be done by the user even if he is not currently logged in... I have done a lot of research but unable to fix this solution. I also found this thread but it seems to have no proper answer:
Spring Security 3.1 - Automatically redirect to login page when session-timeout occurs
For example, most of the banking sites log you out after a time out.. they do not wait until you come back and then submit a request before you are redirected to home page.
HTTP is stateless. To achieve some form of state the server can maintain a session for each user by giving them a session id on their first request. The user would have to resend that session id on each future request to identify that the other requests happen within the same session.
Because the session is maintained by the server, there is no way to notify the client that the session has timed out.
Instead, if the user makes a new request when the session is timed out, their session ID is no longer good and therefore you can take a particular action like redirect them to login page.
Assuming nothing works out. You may want to consider below mentioned approches:
Approach 1:
Create a cookie on browser and have encrypted timestamp in it that will contain last visited/request timestamp from browser, for each request first get get this cookie value and compare with the pre-defined session out time, if session-out time reached then redirect user to error page else serve the request. On logout delete the cookie.
Why encrypted value for timestamp: if somehow user gets to know about cookie used for session timeout then (s)he can change this value in browser and keep on sending this request.
Approach 2:
You can also achieve this by making an entry in your database for every logged-in user and updating timestamp in this database for each request. For each incoming request get this timestamp from database and compare it with pre-defined value for timeout and handle accordingly. On logout delete the entry.
In both the approaches explicitly perform response.redirect("errorPageUrl");
I don't really deeply understand of the session mechanism but just good enough as a casual user of the technology. I have a page implemented with jQuery ajax request. If I keep refreshing the page at a fast pace it would make the session expired and I have to login again. I would appreciate for an explanation of the phenomenon and solution to prevent that.
Sessions consists in to main parameters
Cookies and Server-side session data
In a very little explanation
cookies contains session ID, that references to the server to get session data. Server then fetchs data with the session ID and matches it inside a file with various parameters.
Your problem must be session timeout, it depends mainly on session timeout parameter configured.
Your ajax requests only works if the session timeout hasnt expired thats why it prompts you for login.
You can solve this by defining a service that does not require authentication, you can define your functions on a specific file with no session initialization so the request can bypass the security session, and your other pages that need security are secured at the same time. Like amazon mechanism.
I have a standard HTML login page, which I would much rather use than the standard HTTP authentication pop-up provided by browsers. Today, I am using session cookies to keep track of the session after logging in, but I'd like to be stateless and pass the HTTP authentication every time. The web services I am hitting already support this, so this is a browser-only issue.
Adding authentication credentials is trivial in jQuery, but I don't know how to keep them around. If you go from the login page (a jsp) to the Home page (another jsp) you clearly don't keep the username and password fields from the login page. I know some browsers will store your HTTP authentication credentials if you enter them from the pop-up, but I don't know if they get stored when using an XHRRequest. If they do, is there much consistency among browsers?
Also, the user needs to be able to "sign out" of the application, too. If the browser stores the authentication credentials, is there a way to clear them using JavaScript.
I feel like I can't be the first person to try to solve this. Is there some jQuery plugin or something that already handles this? Or is it simply not possible to do what I'm trying to do?
You have 2 options:
1) Client-side storage of credentials -- not a good idea. For obvious reasons you don't want to store the username/password on the client. If you had a hashed version of the password, it might not be so bad, but still not recommended. In any case, if you're going to store on the client side, you either have to use a cookie, or HTML5 local storage (which is not widely supported, yet)
2) Server-side storage of credentials -- typically done with sessions. Then the resultant Session ID can be passed back to the client and persisted in either a cookie or in the URL of each subsequent AJAX call (?SESSID=xyz for example)
The server-side approach would be the most secure, reliable, and easiest to implement
Okay, I'll take a stab at helping ...
Firstly, understand how HTTP authentication works. There are two versions - Basic and Digest. Basic transmits in plaintext, digest is encrypted. With these types of authentication, the username/password are passed in the HTTP header with every single request. The browser captures these at login and they are stored in an inaccessible browser session cookie which is deleted when the browser session is closed. So, in answer to one of your questions, you can't access these from javascript.
You could create your own session cookie variables for username and password. The jQuery functions for this are really simple. See jquery-cookie module as one example of how to set session cookies. These could be retrieved from the session cookie and sent with each ajax request and validated in the server. However, this is not a particulary good way to do authentication since sniffing the network will allow anybody to easily grab your auth details. But, it would work.
Using session cookie based authentication where the session ID is sent sent with each request is the best way to do this. At the server side, you need to have a function called for every HTTP request. This function should do the following:
check to see if the session has been authenticated
if no:
redirect to login screen
if yes:
do authorization and allow the user access to the page
Most web frameworks support session cookie authentication and the management of session ids at the server. This is definately the way to go.
This is interesting one.
Manage user sessions on server by use of cookies. Create a session when user first accesses the login page and pass the session id/key as value to one of the cookie via response. When the user is authenticated put user "key" info in cookie and "values" in application context at server. Once user is logged, any subsequent request will be authenticated based on session cookie value at server. Authorization will be done based on user "key" passed as cookie value.
On logout clear the session based cookies from server and refresh the site to default page.
Cookies are bizarre with different browsers - just a note ;)
Hope this helps.
Update
The answer below was posted in 2012 and the links are mostly dead. However, since then, a more elegant standards-based approach to the same solution appeared using JSON Web Tokens. Here is a good blog post explaining how to use them.
Most answers miss the point, which is to avoid having any server-side session. I don't want any application state in the server. I'll award the bounty to answer that came closest, but the real credit goes to the rest-discuss group and Jon Moore for the correct answer and to Mike Amundsen for helping me to actually understand it.
The best answer I've gotten is to use a cookie, but not the typical automatic session id cookie given to you by most application servers. The cookie (which will automatically be sent with each subsequent request) is a user identifier and time signed by the server. You can include an expiration time with the cookie so it simulates the typical 30 minute session on a server (which means you have to push it forward with subsequent requests) as well as keeps the same cookie from being valid forever.
The XHR/AJAX part is a red herring. This will work whether you are doing XHR requests or an old-fashioned page-by-page web application. The main points are:
The cookie is automatically sent on subsequent requests so there's no
special scripting required - it's just how browsers work already.
The server does not need to store any session for the user, so the user
can hit any server in a cluster and not have to re-authenticate.
Slightly interesting in that you consider pushing some of the authent to the client. If you want a conventional solution, KOGI's server-side suggestion is the way to go.
But you also seem to be asking questions about memory leaks involving your user supplied secrets. Good questions. But to take a general stab at answering that I'd say it would have to be browser specific. It's browser internals, javascript engine internals -dependent where a client side application (i.e., the browser, or js in the browser) is storing the values the user inputs.
Most likely those values are not replicated needlessly throughout memory, but there's no way to guarantee that. Apart from responsible javascript coding practices, there's nothing you can do to guarantee the limit of locations of user inputs.
Slight digression
The basic point is if you store it on the client it is not really secure -- unless, the serve stores encrypted information on the client with a key that only the server (or the user via their correct credentials), has. So you could conceivably code a JS application to do some authent on the client -- much the same as how bank card (used to?) do POS authent by checking the PIN to the PIN on the card, and not back at the DB. It's based on the (somewhat flimsy) assumption the user has no direct read/write access of the "dark area" cookie/local storage on client / mag strip on bank card. So I would only advise this as disqualifier for false authents and not as a sole qualifier for the credentials.
Main point
If you do want to be stateless, just store user credentials in localstorage, or as a cookie but encrypt them with a server key. When you need them send an XHR with the encrypted / use stored credentials to the server over HTTPS, let your server decrypt them and send them to the callback. Then pass those cleartext of HTTPS to do your authent.
How can I increase the security of my sessions?
$this->session->userdata('userid')
I've been throwing this little bad boy around for my ajax calls. Some cases I haven't. Then I was like, is this really secure using id from the DOM? what if the DOM is changed to hack user accounts data? So then I was like I guess anytime a user is doing something relating to their id, only sessions should be referenced. Am I right?
Referenced like so:
$this->some_model->do_data_stuff($dataId, $this->session->userdata('userid'));
Then I read this:
While the session data array stored in the user's cookie contains a
Session ID, unless you store session data in a database there is no
way to validate it. For some applications that require little or no
security, session ID validation may not be needed, but if your
application requires security, validation is mandatory. Otherwise, an
old session could be restored by a user modifying their cookies.
http://codeigniter.com/user_guide/libraries/sessions.html
I'm not going to be storing financial data but I don't want any data on my site corrupted ever. Does SO use session validation? How much overhead will this validation cost? How would a session be hacked? What are some things to look out for with session security?
Using CodeIgniter sessions with database is going to be fairly secure. You just don't have to trust the input that the user gives. Even if you are using AJAX, the CodeIgniter session will work just like any standard call, so the same security goes on.
What happens with the CodeIgniter session is that the server stores the cookie, and every time the user does an action that would change the content of the cookie, it is first compared to the previous cookie.
If the user changes the content of the session cookie in the browser, CodeIgniter will notice on the next server call, and create a new session for the user, basically logging him out.
CodeIgniter doesn't really need the data stored in the cookie in the user's browser, and as long as you're using
$this->session->userdata('userid');
you're going to get trusted server-side data. The user can't change that. Furthermore, the cookie can be encrypted, and you should have it encrypted. Just look in config.php of CodeIgniter.
There are several other protections around the session data: the short refresh timeout (usually 300 seconds), it checks if the IP changed, and if the browser changed. In other words, in the worst case scenario, the only way to spoof the session data is by having the same version of the browser, having the same IP, getting direct access to the computer to copy/paste the cookie, and getting this done within 5 minutes.
So, watch out for the guy sitting beside you!