How To Crack Password!!!!

Password cracking is the process of attempting to gain un-authorized access to restricted systems using common passwords or algorithms that guess passwords.
In this article, I will introduce you to the most used password cracking techniques.

What is password cracking?

Password cracking is the method of obtaining the correct password that gives access to a system protected by an password. Password cracking employs a number of techniques to arrive at correct password.

What is password strength?

Password strength is the measure of a password’s efficiency to resist password cracking attacks. The strength of a password is determined by;

• Length: the number of characters the password contains.
• Complexity: does it use a combination of letters, numbers and symbol?
• Unpredictability: is it something that can be guessed easily by an attacker?

Let’s now look at a practical example. We will use three passwords namely

1.  password

2.  password1234

3. Password1234!@#$

Password cracking techniques

There are a number of techniques that can be used to crack passwords. We will describe the most commonly used ones below;

• Dictionary attack– This method involves the use of a wordlist to compare against user passwords.
• Brute force attack– This method is similar to the dictionary attack. Brute force attacks use algorithms that combine alpha-numeric characters and symbols to come up with passwords for the attack. For example, a password of the value “password” can also be tried as p@$$word using the brute force attack.
• Rainbow table attack– This method uses pre-computed hashes. Let’s assume that we have database which stores passwords as md5 hashes. We can create another  database that has md5 hashes of commonly used passwords. We can then compare the password hash we have against the stored hashes in the database. If a match is found then we have the password.
• Guess– As the name suggests, this method involves guessing. Passwords such as qwerty, password, admin etc. are commonly used or set as default passwords. If they have not been changed or if the user is careless when selecting passwords, then they can be easily compromised.
• Spidering– Most organizations use passwords that contain company information. This information can be found on company websites, social media such as facebook, twitter etc. Spidering gathers information from these sources to come up with word lists. The word list is then used to perform dictionary and brute force attacks.

Password cracking tool

These are software programs that are used to crack user passwords. We already looked at a similar tool in the above example on password strengths. The website www.md5this.com uses a rainbow table to crack passwords. We will now look at some of the commonly used tools
John the Ripper
John the Ripper uses the command prompt to crack passwords. This makes it suitable for advanced users who are comfortable working with commands. It uses to wordlist to crack passwords. The program is free but the word list has to be bought. It has free alternative wordlists that you can use. Visit the product website http://www.openwall.com/john/ for more information and how to use it.

Cain & Abel
Cain & Abel runs on windows. It is used to recover passwords for user accounts, recovery of Microsoft Access passwords; networking sniffing etc. Unlike John the ripper, Cain & Abel uses a graphic user interface. It is very common among newbies and script kiddies because of its simplicity of use. Visit the product website http://www.oxid.it/cain.html for more information and how to use it.

Ophcrack
Ophcrack is a cross platform windows password cracker that uses rainbow tables to crack passwords. It runs on windows, Linux and Mac OS. It also has a module for brute force attacks among other features. Visit the product website http://ophcrack.sourceforge.net/  for more information and how to use it.

Hacking Activity: Hack Now!

In this practical scenario, we are going to crack a windows account with a simple password. Windows uses NTLM hashes to encrypt passwords. We will use the NTLM cracker tool in Cain and Abel to do that.

Cain and Abel cracker can be used to crack passwords using;

• Dictionary attack
• Brute force
• Cryptanalysis

We will use the dictionary attack in this example. 

For this demonstration, we have created an account called Accounts with the password qwerty on windows 7.

Password cracking steps

• Open Cain and Abel
• Make sure the cracker tab is selected as shown above
• Click on the add button on the toolbar.
• The following dialog window will appear
• The local user accounts will be displayed. Note the results shown will be of the user accounts on your local machine.
• Right click on the account you want to crack. For this tutorial, we will  use  Accounts as the user account.
• Right click on the dictionary section and select Add to list menu as shown above
• Browse to the 10k most common.txt file that you just downloaded
• Click on start button
• If the user used a simple password like qwerty, then you should be able to get the following results.
  

• Note: the time taken to crack the password depends on the password strength, complexity and processing power of your machine.
• If the password is not cracked using dictionary attack, you can try brute force or cryptanalysis attacks.