Advise on generating a new session identifier after successful authentication

1

ISSUE DESCRIPTION:

Currently we use OpenID Connect for user authentication. When a user initially navigates to the application, an ss-id (session identifier) is set. The user is then redirected for authentication. Upon successful authentication, the user is redirected back to the application where the same ss-id is used for the authenticated session.

The reuse of the same ss-id before and after authentication allows for potential session fixation attacks.

Can you please suggest the best way to generate a new, unique session identifier to replace the initial ss-id, Upon successful authentication?
If authentication is successful, what is the best way to create a new session identifier and store it?

2

Please provide your Auth configuration including where the session is stored and URLs that’s used to Authenticate.

3

we are making use of AuthenticateAsync() as below. We are calling the below functions

public abstract override Task<object> **AuthenticateAsync**(IServiceBase authService, IAuthSession session, Authenticate request, CancellationToken token=default);

and then calling Init() which Sets the CallbackUrl and session.ReferrerUrl if not set and initializes the session tokens for the AuthProvider

protected IAuthTokens **Init**(IServiceBase authService, ref IAuthSession session, Authenticate request)

and then we make a call to GetAbsoluteUrl() to get the redirect url

public static string **GetAbsoluteUrl**(this IRequest httpReq, string url)

and we make a call to AddAuthToken() to add AccessToken, RefreshToken, RequestToken to the session
session.AddAuthToken(tokens)

and then we are calling SaveSessionAsync()

public static async Task **SaveSessionAsync**(this IAuthProvider provider, IServiceBase authService, IAuthSession session, TimeSpan? sessionExpiry = null, CancellationToken token=default)

public virtual async Task<IHttpResult> **OnAuthenticatedAsync**(IServiceBase authService, IAuthSession session, IAuthTokens tokens, Dictionary<string, string> authInfo, CancellationToken token=default)

protected virtual AuthContext **CreateAuthContext**(IServiceBase authService=null, IAuthSession session=null, IAuthTokens tokens=null)

override method from ServiceStack AuthenticateAsync will take care of the authentication process, we are expecting to change the session token after successful login. If I use

authService.Request.GenerateNewSessionCookiesAsync(session);
before calling OnAuthenticatedAsync() it is working.

Is this the correct way to handle this? Could you please suggest us the best way to handle this?

4

Yes that’s what should be called, it would normally get called for most Auth Providers at:

Except some OAuth Providers requires additional information stored in the session to correlate the callback so it’s not called then. So if you call Request.GenerateNewSessionCookiesAsync() at the start before authenticating it should generate new session cookies for that request.

5

Thank you for your suggestion. Could you please confirm
authFeature?.HasSessionFeature was introduced in which ServiceStack version?

6

Looks like it was added in this commit on January 2, 2024 so it’s in v8.1.

1 Like
7

Can you please suggest the best approach to handle this in ServiceStack version 6.9 since HasSessionFeature is not available in ServiceStack version 6.9

I am trying with the below code and only before authetication generateNewCookies is true. But in order to generate new session id after successful authentication generateNewCookies value is false.
The public override Task AuthenticateAsync() is called 2 times i.e on hitting the url before authentication and it is called again after successful authentication,
before authentication generateNewCookies value is true but after authentication generateNewCookies value is false. So how can we handle this to generate new session id after successful authentication?

var authFeature = HostContext.GetPlugin<AuthFeature>();
var generateNewCookies = authFeature.GenerateNewSessionCookiesOnAuthentication
  && string.IsNullOrEmpty(Request.QueryString["oauth_token"])
  && string.IsNullOrEmpty(Request.QueryString["State"])
  && string.IsNullOrEmpty(Request.QueryString["state"]);

if (generateNewCookies)
{
    Request.GenerateNewSessionCookiesAsync(session, token).ConfigAwait();
}
8

HasSessionFeature is just a check if the SessionFeature plugin is registered (e.g. HostContext.HasPlugin<SessionFeature>()), you don’t need to check for it in your code as your App is always using it.

I don’t see how authFeature.GenerateNewSessionCookiesOnAuthentication can be false, it’s a singleton that’s initialized on Startup, nothing should be changing it after it’s initialized.

I’d recommend upgrading to the latest version, otherwise you could execute custom logic with a Global Request Filter, e.g:

RegisterTypedRequestFilterAsync<Authenticate>(async (req, res, dto) =>
{
    // implement custom check for when cookies should be regenerated 
    if (MyShouldRegenerateCookies(req)) 
    {
        var session = await req.GetSessionAsync();
        await req.GenerateNewSessionCookiesAsync(session);
    }
});
1 Like
9

I am trying to regenerate a new session id with the below code

                session.AddAuthToken(tokens);

                authService.Request.GenerateNewSessionCookiesAsync(session, token).ConfigAwait();
                var tt = authService.Request.Cookies;

                setSession(tokens.RequestToken, session);

                this.SaveSessionAsync(authService, session, SessionExpiry);

GenerateNewSessionCookiesAsync() is generating a new session id after successful authentication, the newly generated ss-id and ss-pid can be seen in the Response Headers but the old ss-id and ss-pid values still exists in the Request Headers.
whatever ss-id and ss-pid values were there in Response Headers before authentication is now showing in Request Headers after successful authentication.

var tt = authService.Request.Cookies;
here, tt still holds old cookies values(i.e old ss-id and old ss-pid from Response Headers which had got generated before authentication)
Can you please advise on how to get rid of this old values from Request Headers?

10

The Request represents the current HTTP Request and is immutable, i.e. you can’t change the Request Cookies.

Calling the GenerateNewSessionCookiesAsync API should return the new cookies to the client/browser after which their next request should use the new Cookies. You should be able to get the new cookie from the session, e.g:

var sessionId = req.GetSession().Id;
11

Yes i am able to get the new cookie from the session with
var sessionId = req.GetSession().Id;

but when we consider a scenario as below,

  1. Login as User A: Log in as a User A to obtain session identifiers.
  2. Login as User B: Login as as a different user User B in a new browsing session
  3. Manipulate Session IDs: modify User B’s session identifiers to match those of User A by replacing User B’s ss-id with the newly generated ss-id and ss-pid of User A from Response Headers after successful authentication
  4. By replacing User B’s session ID with the valid ss-id of User A from Set-Cookie after authentication, there is a possible vulberability, allowing them to access the application as User A.
    If User B can successfully access User A’s account, it indicates that the application is vulnerable to session fixation.

even with the newly generated ss-id and ss-pid in the Response Headers, after following the above steps, I see the new ss-id and ss-pid of User A being manipulated and used by User B, allowing the access as User A
so can you please advise how i can handle this scenario?

12

Don’t let users re-login if they’re already authenticated. Have User A logout first to delete their cookies then login as User B.

You could force this by having the login page link to an API that deletes the cookies then redirects to the login page (e.g. /auth/logout?continue=/mylogin). Or in your login page, use JS to log them out (e.g. await client.api(new Authenticate({ provider:'logout'})) before attempting to log them in.

13

right now in my code without generating any new session cookies, as soon as I hit the Url i.e Before Authentication, it hits
AuthenticateAsync(IServiceBase authService, IAuthSession session, Authenticate request, CancellationToken token = default)
wherein at this point, authService.Response has some Cookies value(ss-id and ss-pid) and authService.Request has some Cookies value(ss-id and ss-pid)

After this, I will be redirected to Pick an account and enter credentials & Sign in.
Just before successful authentication and launching the page it hits AuthenticateAsync() for the 2nd time.
This time,
authService.Response.Coookies does not have any ss-id and ss-pid i.e authService.Response.Coookies.Collection.Count=0
but authService.Request.Coookies has ss-id and ss-pid values which is nothing but the old Cookies value which had got generated in Response Headers Before Authentication

before redirection and successfuly launching the page I am making the below calls
session.AddAuthToken(tokens);
this.SaveSessionAsync(authService, session, SessionExpiry);

Now, when I consider a scenario as below :

  1. Login as User A: Log in as a User A to obtain session identifiers.
  2. Login as User B: Login as as a different user User B in a new browsing session
  3. Manipulate Session IDs: modify User B’s session identifiers to match those of User A by replacing User B’s ss-id with the Cookie: ss-id and ss-pid of User A from Request Headers after successful authentication of User A
    By replacing User B’s session ID with the valid ss-id of User A from Cookie after authentication, there is a possible vulberability, allowing User B to access the application as User A.
    If User B can successfully access User A’s account, it indicates that the application is vulnerable to session fixation.

So how do I handle this? Please advise

14

Wait, what. Are you hijacking another user’s session ids and you’re surprised you can impersonate them?

15

I am aiming to identify potential vulnerabilities, specifically session fixation, to ensure the application is secure. I’m looking for guidance on how to properly handle session management to prevent such vulnerabilities.

16

Stealing someone else’s session cookies means you can impersonate them. This is how session based authentication and cookies work, it’s working as designed.

Use a different Auth Provider if you don’t want to use Session/Cookies.