[keycloak-dev] AbstractUsernameFormAuthenticator validateUserAndPassword process

[Marek Posolda]

On 01/04/16 09:41, Marek Posolda wrote:
> On 31/03/16 18:17, Ariel Carrera wrote:
>> Marek, that's makes sense, but, what happen when the user is known by 
>> the attacker? If the brute force check is in the "isEnabled" method 
>> (after password validation), the attacker guesses the password 
>> successfully, the brute force protection never apply. Please check 
>> the code because i am afraid that it can be a big security risk.
>> If you wants I can open a new jira issue to discuss about it.
> Hmm... I am missing the scenario where exactly is the security risk? 
> Could you elaborate more? What I can see is:
>
> - In case that attacker knows both username and password of user, the 
> security is compromised anyway. In this case, Keycloak don't have 
> possibility to differ between valid user (who knows his username and 
> password) and attacker (who knows both username and password). So in 
> case that user is enabled, both valid user or attacker are able to 
> login. In case that user is disabled, both valid user and attacker 
> will receive message "Account is disabled" (because "validatePassword" 
> check passes, but "enabledUser" check fails)
>
> - In case that attacker knows just username, the "validatePassword" 
> check will fail and will be "logged" in BruteForce too. Attacker will 
> receive message "Incorrect username or password"
Also one more point, if user account is temporarily disabled because of 
BruteForce protection, attacker won't recognize it because message will 
still be "Incorrect username or password" . He won't know that he 
guessed password. We added this recently, see some related discussion 
here : http://lists.jboss.org/pipermail/keycloak-dev/2016-March/006751.html

Marek
>
> Marek
>
>>
>> 2016-03-31 7:44 GMT-03:00 Marek Posolda <mposolda at redhat.com 
>> <mailto:mposolda at redhat.com>>:
>>
>>     AFAIK one of the reasons is security. If an attacker guesses
>>     username "foo", which exists, but not password of user "foo", you
>>     don't want to tell him that he successfully guessed username. So
>>     instead of first checking that user "foo" is disabled and display
>>     the message "The user account is disabled", you rather check
>>     password first and then display the message "Incorrect username
>>     or password", so attacker don't have a clue if account really
>>     exists or password was incorrect etc. Also if BruteForce
>>     protector is enabled, you want to log the event as failed login,
>>     so we're checking the password of user.
>>
>>     Marek
>>
>>
>>
>>     On 30/03/16 17:40, Ariel Carrera wrote:
>>>     Hi, I am developing a Federation Provider, and I have a question...
>>>
>>>     Why the method () checks if the user "is enabled" after validate
>>>     the password instead of before of the password validation?
>>>
>>>     AbstractUsernameFormAuthenticator.validateUserAndPassword: line
>>>     141/151
>>>     ...
>>>             if (invalidUser(context, user)){
>>>                 return false;
>>>             }
>>>
>>>     *        if (!validatePassword(context, user, inputData)){*
>>>     *            return false;*
>>>     *        }*
>>>
>>>     *        if(!enabledUser(context, user)){*
>>>     *            return false;*
>>>     *        }*
>>>     ...
>>>
>>>     If the user is disabled... why validate his password and return
>>>     a password validation error message?
>>>
>>>     -- 
>>>     Ariel Carrera
>>>
>>>
>>>     _______________________________________________
>>>     keycloak-dev mailing list
>>>     keycloak-dev at lists.jboss.org <mailto:keycloak-dev at lists.jboss.org>
>>>     https://lists.jboss.org/mailman/listinfo/keycloak-dev
>>
>>
>>
>>
>> -- 
>> Tatú
>

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