When a use is logged in (Through open-id) we are creating a session variable named "UID" and storing the unique user-id in it. Later we are checking the session to see if the user is logged in. I think this is not the right way, but I could not force the team to change this, as I cannot show how this implementation can be cracked. Can anybody show me why (If yes) this implementation is bad?
I can see no situation where you should worry about a server-side Session value being obtained through a client-side exploit. There has been some concern about fake OpenID providers tricking users into passing credentials because of the lack of stature to OpenID, but generally it's unwarranted.
The implementation seems acceptable, but given that you are using ASP.NET you should consider using IIdentity and this ASP.NET OpenID provider:
http://code.google.com/p/dotnetopenid/
It's well tested and has quite a bit of security code and API support built into it.
My first question would be, what is making you think this is not the right way?
Storing data in this way is very common, secure and it's localized specifically to a user. If you don't like using the session for other reasons such as handling sessions over multiple servers or having to serialize / deserialize the session to a data store (assuming non-memory session) then that is a different arguement but the security part shouldn't be the issue.
Also keep in mind the simplicty of using the session as well. It makes data access to user specific data that you need to access constantly, standard and consistent throughout your application.
EDIT based on comments:
I was wondering the same thing when I started using MVC as well and it seems to be totally fine. I couldn't find anything against the idea. I even asked this question because my custom authorize attribute had to access the session and I stored special role types in it that the out of the box authorization didn't quite fit.
As Nissan Fan stated, I can see no reason you should be fearful of a server-side session value being exploited.
Just out of curiosity, what are some of your reasons for thinking it's not the right way to go?
Related
Apparently I inherited a severe security issue.
User can login and be at this URL
https://ourdomain.com/User/Index
but problem is the user can put in
https://ourdomain.com/User/Edit/16642 and have ACCESS
what is the easy solution to fixing this?
This is a vulnerability that is sometimes called 'forced browsing'.
The short answer to your question is that there is no easy way. You have to implement authorization, and that is painful to retrofit into an existing application.
First, you need authentication (ie. users being able to securely log on). I suppose this is already done more or less, otherwise ~/User/Index would be meaningless. (Btw if there is such a vulnerability in the site, you should probably have a look at authentication too, but if standard stuff like forms auth is used, then that is easier to get right.)
Then you need authorization, possibly on two different levels. For each and every call (ie. controller action in MVC), you need to decide, whether the logged on user is allowed to make the call. In .Net MVC a relatively easy way to implement this is Membership and the Authorize attribute.
Then depending on the functionality, you may also need fine-grained authorization. For example if your application stores lists of books assigned to specific users with other users not having access, the application needs to decide whether a ~/ShowList/123 request can be fulfilled, based on the logged on user and the specific list with id=123 (it's not enough to say that a logged on user can call ~/ShowList because it depends on which one). This is called resource-based authoriozation in Microsoft terms and is discussed here. If you don't have such distinction between subjects (users) and objects (book lists) of the same type, you may not need this at all.
If your inherited application is large, any of this is painful to implement, but there really is no very easy shortcut unfortunately. You can do it differently, but anything that is much less work than this will probably be flawed, unless your use-case is very specific.
Also please note that Angular doesn't have much to do with this. All authorization must be implemented on the server side, otherwise it's useless.
I have an ASP.NET application that uses a custom MembershipProvider to allow users to log in and gain access to certain features. The MembershipProvider uses ASP.NET's built-in forms authentication to set cookies and keep track of who the user is.
Now that I've got the user logged in, what's the best way to store user-specific information for their session? In the past I've just used Session variables ie Session["ReputationLevel"] = "4230"; (my application doesn't actually have a reputation level variable, this is just an example). Is this still the best way when using a MembershipProvider? Would it be better to somehow build this information into the provider itself, or into a custom MembershipUser implementation? If I keep everything in the session, I suppose I'd have to abandon the session when the MembershipProvider indicates that the user had logged out...?
Sorry if this question is vague. I've been doing mostly ColdFusion development for the past few years, and I'm still kinda new to some of these ASP.NET technologies. I thought the MembershipProvider functionality would take care of everything I needed, but I'm now seeing there are still some holes in my implementation (in this case, where to store additional data).
This question appears to be similar, but doesn't appear to be quite what I'm asking.
If you want to persist the information beyond the session, it's probably best to store it by user in your database. There are several ways to do this:
You can roll your own by manually storing and reading in data from a SQL table as needed -- possibly using the runtime cache to save from hitting the db on every request.
You can extend MemberShipUser in your custom membership provider and add the properties to it. Here is a walkthrough...
You can use ASP.NET Profiles, which might be the easiest way to go and it supports storing data for unique unauthenticated users as well. Here's a walkthrough for profiles, although there are several more out there.
I'm not sure how you would do it, but I suppose you could extend the Membership provider to do that. But personally, I've found that ordinary sessions work just fine. Only thing I'd do is to wrap their functionality in a a set of shared functions. So your example would be:
static string GetUserReputation()
{
return Session["Reputation"].ToString();
}
and just call GetUserReputation
I'm porting an ASP.NET application to MVC and need to store two items relating to an authenitcated user: a list of roles and a list of visible item IDs, to determine what the user can or cannot see.
We've used WSE with a web service in the past and this made things unbelievably complex and impossible to debug properly. Now we're ditching the web service I was looking foward to drastically simplifying the solution simply to store these things in the session. A colleague suggested using the roles and membership providers but on looking into this I've found a number of problems:
a) It suffers from similar but different problems to WSE in that it has to be used in a very constrained way maing it tricky even to write tests;
b) The only caching option for the RolesProvider is based on cookies which we've rejected on security grounds;
c) It introduces no end of complications and extra unwanted baggage;
All we want to do, in a nutshell, is store two string variables in a user's session or something equivalent in a secure way and refer to them when we need to. What seems to be a ten minute job has so far taken several days of investigation and to compound the problem we have now discovered that session IDs can apparently be faked, see
http://blogs.sans.org/appsecstreetfighter/2009/06/14/session-attacks-and-aspnet-part-1/
I'm left thinking there is no easy way to do this very simple job, but I find that impossible to believe.
Could anyone:
a) provide simple information on how to make ASP.NET MVC sessions secure as I always believed they were?
b) suggest another simple way to store these two string variables for a logged in user's roles etc. without having to replace one complex nightmare with another as described above?
Thank you.
Storing the user's role information in a server-side session is safe providing a session cannot be hijacked. Restating this more broadly, it does not matter where user role info is stored if an authenticated session is hijacked.
I advise not putting too much faith in the article you linked to, but the 2002 vintage report linked to from your link is of interest. Here are my take-aways:
Don't accept session IDs embedded in URLs.
Focus your time on eliminating cross site scripting dangers i.e. scan all user supplied data and parse out executable java script.
Issue cookies for complete domains (e.g. myapp.mydomain.com)
Host your domain at a high class DNS operator e.g. one that only allows DNS changes from a preset remote IP address.
Don't issue persistent session cookies.
Reissue a session cookie if someone arrives at a login page with a sessionID already associated with an authenticated session.
Better still, always issue a new session cookie on successful authentication and abandon the prior session. (Can this be configured in IIS?)
The only way to make a secure cinnection is to use SSL. Anything less than that, and you simply have to make the evaluation when it's "safe enough".
A session variable works fine for storing a value, with the exception that the web server may be recycled now and then, which will cause the session to be lost. When that happens you would have to re-authenticate the user and set the session variable again.
The session variable itself is completely safe in the sense that it never leaves the server unless you specifically copy it to a response.
Have you considered setting up a custom Authorize tag in MVC. I gave an example of this in another question.
On initial authorization (sign-in screen or session start) you could seed a session value with the IP address also. Then in your custom authorization, you could also verify that IP's still match up as well. This will help make sure that someone isn't 'stealing' the person's session. Everytime you access your session data just make sure to pass the requester's IP and have some check on it.
Are you trying to control the access to functions at the client level? That is the only reason I would expose the roles and items to control client side functions.
Alternatively, you could create a function to obtain the items that the roles of the user are allowed to use, and then even if the function is called outside of the items given back to the web application, you can prevent the user from accessing them.
4Guys seems to show how to control functions with the roles.
The approach I have used in the past is to use symmetric encryption of a cookie alongside SSL. Encrypt the user information in the reponse and decrypt it in the request. I'm not claiming this is foolproof or 100% secure and I wouldn't want to do this on a banking application, but it is good enough for many purposes.
The main issue with session variables is that if you store them inProc rather than persisting them, then you need to apply 'sticky' sessions to your load balancing in a web farm environment. Guffa is correct that without this persistence session variables will occasionally be lost causing a poor user experience.
Sticky sessions can lead to uneven load balancing, perhaps reducing the value of being able to scale out.
If you are going to be be persisting the sessions so they can be accessed by all servers in your web farm, you may be better off using a Guid to identify the user, encrypting this in a cookie and retrieving the user record from your data store each time.
My obvious question is that why do you want to store a users role in session ?
Here is my answer to your query, how this helps. I have attached a small demo application for you to take a look at and understand my points. When you open this project in visual studio, click on the project tab on the top and select asp.net configuration. From the page that will show up you can do the user administration stuff.
You need to store the roles of a user in some secure manner ? The answer to this question is that there is no need for you to worry about storing the role for any user, when we have the asp.net membership, profiles and roles framework to help us out on this. All you need to do is create a role in the aspnet database and assign that role to the user.
Next you want to store two string in some secure manner. I suggest you user profile for storing user specific information. This way you have the information available to you where ever you want from the profilecommon class.
Also please see the attached demo application placed at the end of my blog http://blogs.bootcampedu.com/blog/post/Reply-to-httpstackoverflowcomquestions1672007user-roles-why-not-store-in-session.aspx
Just a suggestion, you might consider using this little library:
http://www.codeproject.com/KB/aspnet/Univar.aspx
It has a server side implementation of the cookie whereby all cookies can be stored on the server while asp.net authentification is used to identify the user. It supports encryption and is also very flexible making it very easy to switch from one storage type to another.
What's the best way to authenticate and track user authentication state from page to page? Some say session state, some say cookies?
Could I just use a session variable that has the ID of the user and upon authentication, instatiate a custom User class that has the User's information. Then, on every page, verify the session variable is still active and access basic user data from the User object?
Any thoughts? Any good examples?
The problem with favoring sessions over cookies for 'security' is that sessions USE cookies to identify the user, so any issue with cookies is present with sessions.
One thing to keep in mind with the use of Sessions is data locality. If you plan to scale to more than one webserver at any point, you need to be very careful storing large amounts of data in the session objects.
Since you are using .NET, you will basically have to write your own session store provider to handle this, as InProc won't scale past 1 server, the DB provider is just a bad idea entirely (The whole point is to AVOID DB reads here while scaling, not add more), and the StateServer has a lot of capacity issues. (In the past, I have used a memcached session store provider with some success to combat this issue).
I would google for signed cookies and look into using that instead of either regular cookies or sessions. It solves a lot of the security concerns, and removes the locality issues with sessions. Keep in mind they come back and forth on every request, so store data sparingly.
There's no perfect way to do it. If you store it in a cookie you'll take flak that cookies can be stolen. If you store it in the session you'll take flak because sessions can be hijacked.
Personally, I tend to think a session is a little more reliable because the only thing stored on the client is a session key. The actual data remains on the server. It plays the cards a little closer to the chest, if you will. However, that's just my preference, and a good hacker would be able to get past shoddy security regardless.
No matter what you do, don't try to implement this yourself. You'll get it wrong. Use the authentication system provided by your specific platform. You also need to make sure you have adequate security precautions protecting the authentication token.
I dont know if its THE BEST way to do it, but we are comfortable with the way we do it.
we have a custom user object that we instantiate when the user authenticates, we then use Session to maintain this object across the application.
In some application we combine it with the use of cookies to extend the session continuously.
Cookies and Sessions by themselves are not truly sufficient. They are tools to use to track the user and what they do, but you really need to think about using a database to persist information about the user that can also be used to secure the application.
Sessions are Cookies...
Working inside the context of an ASP.NET application I am creating a page that will be able to execute database scripts against one of many databases in our environment. To do this we need to prompt the user for a username/password combination, this value can be used for all servers without issue.
The question is where is the most secure location to store this information? We need to store it temporarily as when they are on this specific page they could be executing hundreds of scripts, over multiple postbacks. From what I can tell I have 3 options and I'm not sure what is the best. Below is my take on the options, what is the recommendation of everyone here? What is the most secure, while still being friendly for the user?
Store Information In Viewstate
One of the first ideas we discussed was storing the information after being supplied by the user in the ViewState for the page. This is helpful as the information will only exist for the lifetime of the page, however, we are unsure of the security implications.
Store information in Session
The next idea we had was to store it in session, however, the downside to this is that the information can be made available to other pages inside the application, and the information always lingers in memory on the server.
Store Information in Application
The last idea that we had was to store it in the Application cache, with a user specific key and a sliding 5 minute expiration. This would still be available to other pages, however, it would ensure that the information is cached for a shorter period.
Why?
The final question that is important is "Why are you doing this?". Why don't we just use their Lan id's? Well we cannot use lan id's due to the lack of network support for delegation.
S0 what is the recommended solution? Why? How secure is it, and can we be?
Update
Great information has been discussed. TO clarify, we are running in an intranet environment, we CANNOT use Impersonation or Delegation due to limitations in the network.
In my opinion the natural place for this is the Session.
I'm not sure why you seem to be fearing "other pages inside the application" (you control the appliciation, don't you?), but if you really are, you could use some sort of encryption before you store it.
But if you are going to do that, the data could live in the ViewState as well.
I don't like any of these ideas, but totally hate the viewstate idea.
I don't know how many databases you are attaching to, but if there is a limited number, I kind of wonder if handling your authentication and authorization in a standard secure manner, then connect to those databases via integrated security using identity impersonation with an account that has minimal permissions.
The ViewState approach is good but has the problem that you are giving out the username and password to the client. Even if you encrypt it, if some attacker has the encryption key, the situation will not be very good.
Regarding the Session and Application approaches, I don't think Application approach makes sense. Data is user specific, so Session should be the way to go. It'll go away as soon as user's session is closed. By the way, if you chose to store it at the server, use SecureString class.
As John MacIntyre wrote you should use integrated security and impersonation for this.
If for some reason you can not use it and you are going to provide your own login page, use by all means SSL to encrypt the traffic between the browser and your server. Using the ViewState approach is also completely insecure if you do not use SSL, there are tools to view the contents very easily. From the methods that you enumerate the best one would be to use the Session state. You can offload saving the session state from your web server memory and save that data in a database that you can secure the way you want. If you don't like the way these work you could even write your own session state provider and apply the security you need there.
Storing in Viewstate increases your exposure because the password will be flying around the internet again and again. It's up to you if encryption is good enough to address this risk.
Using Application or Session both keeps the password in the server. As mentioned above SecureString will keep people from simply reading passwords out of memory. Session will scale to more users, and probably more importantly to multiple servers much easier than Application. Unless you are sure you will never use more than 1 web server I would not use Application, as it will be up to you to synchronize all the servers.
Never store passwords!
Rather store the hash of a password. See: http://en.wikipedia.org/wiki/Crypt_(Unix)#Library_Function.
I'm aware this does not answer the question, but the more programmers who ignore this advice, the easier it will be for criminals to steal data. Don't let your organization become a news story.
The username/password really shouldn't be stored anywhere.
You store a live database connection, preferably from a pool in your Session object. You only need the username/password as long as it takes to log into the database.
While another page can use the live connection, it doesn't give anyone else permanent access to the database as you would by storing a username/password.