Mutillidae  is a free, open source, vulnerable web-application providing a target for web-security tester. Mutillidae can be installed on Linux and Windows using LAMP, WAMP, and XAMMP.

Username Enumeration :- We have an application that will reveal to us when a username exists on the system which can be used in further step like brute-force account.

In Mutilliade login page , when you provide valid username & invalid password , web-application reply us that password incorrect.



When we provide invalid username ; then application tell us that Account does not exist.


So by monitoring web-application message one can know that username is valid or not.

First we will examine source code of page ; when we provide valid username reply is "var lAuthenticationAttemptResultFlag = 1" & when we provide invalid username reply is "var lAuthenticationAttemptResultFlag = 0"

var lAuthenticationAttemptResultFlag = 1    It means username exist.

var lAuthenticationAttemptResultFlag = 0    It means username does not exist.



Alternatively we can do this by saving both page (valid username & invaild username) source code in text file & then use diff command.

root@bt:~# diff login password
762c762
< var lAuthenticationAttemptResultFlag = 0;
---
> var lAuthenticationAttemptResultFlag = 1;

Now Open burpe suite, setup listener ; try to sign in from browser & capture request.


Now right click on request & click on send  to inrtuder.

For position we choose only username.


On payload tab  ---) payload option  ----) load sample username list.


In option tab      ---)    Grep match     ---) Add
var lAuthenticationAttemptResultFlag = 1; var lAuthenticationAttemptResultFlag = 0;


Click on intruder ---) start Attack

Now Burpe make request to login page & examine request & classified responce according to option which we provided.


Click on save , result table & Delimiter click on custom & put ";" ,then select column which we need , in this case i select payload,var lAuthenticationAttemptResultFlag = 1,var lAuthenticationAttemptResultFlag = 0 and then save it.


Saved file is look like following format.


In file first is username ; then true means username exist , false menas username is invalid. So now we only need entry which second column is true.


So i saved this value in another temp file from where you can extract username from file using delimiter. I used simple python script for this purpose.

Finally we got list of username which exist on system.