cudaHashcat or oclHashcat or Hashcat on Kali Linux got built-in capabilities to attack and decrypt or Cracking WPA2 WPA with Hashcat – handshake .cap files. Only constraint is, you need to convert a .cap file to a .hccap file format. This is rather easy.

Hashcat

Hashcat is the self-proclaimed world’s fastest CPU-based password recovery tool. It is available free of charge, although it has a proprietary codebase. Versions are available for Linux, OSX, and Windows and can come in CPU-based or GPU-based variants. Hashcat currently supports a large range of hashing algorithms, including: Microsoft LM Hashes, MD4, MD5, SHA-family, Unix Crypt formats, MySQL, Cisco PIX, and many others.
Hashcat has made its way into the news many times for the optimizations and flaws discovered by its creator, which become exploited in subsequent hashcat releases. (For example, the flaw in 1Password’s hashing scheme)

Attack types

Hashcat offers multiple attack modes for obtaining effective and complex coverage over a hash’s keyspace. These modes are:

Brute-Force attack
Combinator attack
Dictionary attack
Fingerprint attack
Hybrid attack
Mask attack
Permutation attack
Rule-based attack
Table-Lookup attack
Toggle-Case attack

The traditional bruteforce attack is considered outdated, and the Hashcat core team recommends the Mask-Attack as a full replacement.

Variants

Hashcat comes in two main variants:

Hashcat – A CPU-based password recovery tool
oclHashcat – A GPU-accelerated tool

Many of the algorithms supported by Hashcat can be cracked in a shorter time by using the well-documented GPU-acceleration leveraged in oclHashcat (such as MD5, SHA1, and others). However, not all algorithms can be accelerated by leveraging GPUs. Bcrypt is a good example of this. Due to factors such as data dependant branching, serialization, and Memory (to name just a few), oclHashcat is not a catchall replacement for Hashcat.
Hashcat is available for Linux, OSX and Windows. oclHashcat is only available for Linux and Windows due to improper implementations in OpenCL on OSX

Important Note: Many users try to capture with network cards that are not supported. You should purchase a card that supports Kali Linux including injection and monitor mode etc. A list can be found in 802.11 Recommended USB Wireless Cards for Kali Linux. It is very important that you have a supported card, otherwise you’ll be just wasting time and effort on something that just won’t do the job.

Why use Hashcat for cracking WPA WPA2 handshake file?

Pyrit is the fastest when it comes to cracking WPA2 WPA handshake files. So why are we using Hashcat to crack WPA2 WPA handshake files?

Because we can?
Because Hashcat allows us to use customized attacks with predefined rules and Masks.

Now this doesn’t explain much and reading HASHCAT Wiki will take forever to explain on how to do it. I’ll just give some examples to clear it up.
Hashcat allows you to use the following built-in charsets to attack a WPA2 WPA handshake file.

Built-in charsets

?l = abcdefghijklmnopqrstuvwxyz
?u = ABCDEFGHIJKLMNOPQRSTUVWXYZ
?d = 0123456789
?s = !”#$%&'()*+,-./:;⇔?@[\]^_`{|}~

?a = ?l?u?d?s

Capture handshake with WiFite

Why WiFite instead of other guides that uses Aircrack-ng ? Because we don’t have to type in commands..
Type in the following command in your Kali Linux terminal:
root@kali:# wifite –wpa You could also type in
root@kali:#wifite wpa2 If you want to see everything, (wep, wpa or wpa2, just type the following command. It doesn’t make any differences except few more minutes
root@kali:#wifiteOnce you type in following is what you’ll see.

So, we can see bunch of Access Points (AP in short). Always try to go for the ones with CLIENTS because it’s just much faster. You can choose all or pick by numbers. See screen-shot below

Awesome, we’ve got few with clients attached. I will pick 1 and 2 cause they have the best signal strength. Try picking the ones with good signal strength. If you pick one with poor signal, you might be waiting a LONG time before you capture anything ... if anything at all.
So I’ve picked 1 and 2. Press Enter to let WiFite do it’s magic.

Once you press ENTER, following is what you will see. I got impatient as the number 1 choice wasn’t doing anything for a LONG time. So I pressed CTRL+C to quit out of it.
This is actually a great feature of WIfite. It now asks me,
What do you want to do?

[c]ontinue attacking targets
[e]xit completely.

I can type in c to continue or e to exit. This is the feature I was talking about. I typed c to continue. What it does, it skips choice 1 and starts attacking choice 2. This is a great feature cause not all routers or AP’s or targets will respond to an attack the similar way. You could of course wait and eventually get a respond, but if you’re just after ANY AP’s, it just saves time.

And voila, took it only few seconds to capture a handshake. This AP had lots of clients and I managed to capture a handshake.
This handshake was saved in /root/hs/BigPond_58-98-35-E9-2B-8D.cap file.
Once the capture is complete and there’s no more AP’s to attack, Wifite will just quit and you get your prompt back.

Now that we have a capture file with handshake on it, we can do a few things.

Cleanup your cap file using wpaclean

Next step will be converting the .cap file to a format cudaHashcat or oclHashcat or Hashcat on Kali Linux will understand.
Here’s how to do it:
To convert your .cap files manually in Kali Linux, use the following command

wpaclean <out.cap> <in.cap>

Please note that the wpaclean options are the wrong way round. <out.cap> <in.cap> instead of <in.cap> <out.cap> which may cause some confusion.
In my case, the command is as follows:

root@kali:#wpaclean hs/out.cap hs/BigPond_58-98-35-E9-2B-8D.cap

Convert .cap file to .hccap format

We need to convert this file to a format cudaHashcat or oclHashcat or Hashcat on Kali Linux can understand.
To convert it to .hccap format with “aircrack-ng” we need to use the -J option

root@kali:#aircrack-ng <out.cap> -J <out.hccap>

Note the -J is a capitol J not lower case j.
In my case, the command is as follows:

root@kali:#aircrack-ng hs/out.cap -J hs/out

Cracking WPA2 WPA handshake with Hashcat

cudaHashcat or oclHashcat or Hashcat on Kali Linux is very flexible, so I’ll cover two most common and basic scenarios:

Dictionary attack
Mask attack

Dictionary attack

First we need to find out which mode to use for WPA2 WPA handshake file. I’ve covered this in great length in Cracking MD5, phpBB, MySQL and SHA1 passwords with Hashcat on Kali Linux guide. Here’s a short rundown:

root@kali#cudahashcat --help | grep WPA

So it’s 2500.
Now use the following command to start the cracking process:

root@kali#cudahashcat -m 2500 /root/hs/out.hccap /root/rockyou.txt

Bingo, I used a common password for this Wireless AP. Took me few seconds to crack it. Depending on your dictionary size, it might take a while.
You should remember, if you’re going to use Dictionary attack, Pyrit would be much much much faster than cudaHashcat or oclHashcat or Hashcat. Why we are showing this here? Cause we can. :)

2. Brute-Force Attack

Now this is the main part of this guide. Using Brute Force MASK attack.
To crack WPA WPA2 handshake file using cudaHashcat or oclHashcat or Hashcat, use the following command:

Sample:

root@kali#cudahashcat -m 2500 -a 3 capture.hccap ?d?d?d?d?d?d?d?d

Where -m = 2500 means we are attacking a WPA2 WPA handshake file.
-a = 3 means we are using Brute Force Attack mode (this is compatible with MASK attack).
capture.hccap = This is your converted .cap file. We generated it using wpaclean and aircrack-ng.
?d?d?d?d?d?d?d?d = This is your MASK where d = digit. That means this password is all in numbers. i.e. 7896435 or 12345678 etc.
I’ve created a special MASK file to make things faster. You should create your own MASK file in similar way I explained earlier. I’ve saved my file in the following directory as blackmoreops-1.hcmask.

root@kali#/usr/share/oclhashcat/masks/blackmoreops-1.hcmask

Do the following to see all available default MASK files provided by cudaHashcat or oclHashcat or Hashcat:

root@kali#ls /usr/share/oclhashcat/masks/

In my case, the command is as follows:

root@kali#cudahashcat -m 2500 -a 3 /root/hs/out.hccap  /usr/share/oclhashcat/masks/blackmoreops-1.hcmask

Sample .hcmask file

You can check the content of a sample .hcmask file using the following command:
root@kali# tail -10 /usr/share/oclhashcat/masks/8char-1l-1u-1d-1s-compliant.hcmask

Edit this file to match your requirement, run Hashcat or cudaHashcat and let it rip.

Location of Cracked passwords

Hashcat or cudaHashcat saves all recovered passwords in a file. It will be in the same directory you’ve ran Hashcat or cudaHashcat or oclHashcat. In my case, I’ve ran all command from my home directory which is /root directory.

Conclusion

This guide explains a lot. But you should read Wiki and Manuals from www.hashcat.net to get a better understanding of MASK and Rule based attacks because that's the biggest strength of Hashcat.
Thanks for reading. Feel free to share this article.