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Cracking WPA/WPA2 – PSK Encryption

When Wi-Fi was first developed in the late 1990s, Wired Equivalent Privacy was created to give wireless communications confidentiality. WEP, as it became known, proved terribly flawed and easily cracked.

As a replacement, most wireless access points now use Wi-Fi Protected Access II with a pre-shared key for wireless security, known as WPA2-PSK. WPA2 uses a stronger encryption algorithm, AES, that’s very difficult to crack—but not impossible.

The weakness in the WPA2-PSK system is that the encrypted password is shared in what is known as the 4-way handshake. When a client authenticates to the access point (AP), the client and the AP go through a 4-step process to authenticate the user to the AP. If we can grab the password at that time, we can then attempt to crack it.

In this tutorial, I’m going to hack into a Wi-Fi hotspot that I just set up, named – Anonymus.
Now, given that we have Kail Linux, open up a terminal window, type in “ifconfig “. This is going to list all the networking interfaces connected to your device.

Here, we only need (wlan0) which is our Wi-Fi card, so we can disable the others by doing “ifconfig <name of the interface> down”.
(“lo” does no matter)…

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Now, we type “airmon-ng start wlan0”

(airmon-ng is just a tool for monitoring air traffic, “start” basically starts the tool, and “wlan0” specifies the interface we are using for monitoring)
It’ll probably show “some processes that could cause trouble”, we’ll simply kill those processes by entering “kill <process ID>”.

Now if we do “ifconfig”, it should show us the newly made monitoring interface “mon0”.

Then, put in, “airodump-ng mon0”.
In the screenshot below, the highlighted bssid is our target (and it is my own), named “Anonymus”, the channel is 13 as we can see under the “CH” column.

For our next step we type in, “airodump-ng –c <channel> -w <name> –bssid <bssid> mon0”.

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Let me explain a few things here, “airodump-ng” is a tool for capturing Wi-Fi packets, “<channel>” means the channel your target is running on, “-w” basically writes a file by the name that succeeds it in “<name>”, (I did “handshake” just for the convenience of it) bssid is a string of numbers specific to a hotspot.

Now, open up a new terminal and type in “aireply-ng -0 0 –a <bssid> mon0”, this command send a deauthentication signal (usually called a deauth packet) to all the devices connected to that hotspot. Then after a few seconds we stop it by “Ctrl+C”. Now, as we can see, the other terminal shows that the WPA Handshake was successfully captured.

We can close both windows at this point, and open a new one. Type “ls”; that should list the files in the current directory. We can clearly see that the files from the above operation are present. But we only need the file ending with “-01.cap”.

Then we do, “aircrack-ng –w <full location of the wordlist> <the file name>”.

You may be asking what wordlist? What is that sh*t?

A Wordlist is a file containing thousands of known and possible passwords, which you can download from the internet. The one I used can be found here. The list contains 982,963,904 words exactly all optimized for WPA/WPA2.

It will then start searching for matching keys in the word list. Now the time that this will take is solely dependent on the strength of the password. The stronger the password the more time will it take.

After completion it looks something like the screenshot below. In it, you can see that it tested 45688 keys and my key was the 45689th.

Now that we know the password, lets test it…

Successfully connected to your wifi connection!

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