Ophcrack is a program for Windows that allows you to guess a password for logging into XP, Vista or 7 editions of the Microsoft OS. The tool uses various vulnerabilities, as well as rainbow tables to find the correct key. It is also possible to launch the application from removable storage devices such as a USB drive before the operating system loads.

Principle of operation

In order to ensure the security of user passwords, the computer does not store them as simple text, but calculates a cryptographic hash function that is written to a separate file. It also stores the login modifier.

However, you can easily find hash values for simple and common passphrases, and use them to search for authorization credentials. Please note, the longer the password, the more space is required to store the function values.

Rainbow tables work as an alternative capture method in which only the first elements of hash chains are stored. This increases the password guessing time, but significantly reduces the amount of RAM required.

Accessing the system

As for the process itself, all you need to do is run the utility and provide the path to the hash or encrypted SAM file. Next, you can load the rainbow tables and click on the Crack button. The password search time depends on its length and overall complexity.

In addition, you have the ability to create a bootable drive and write the image with the program to it. To do this, you can use such tools as Easy USB Creator or DAEMON Tools.

Features

free to download and use;
compatible with modern Windows versions;
gives you the ability to decrypt passwords for system accounts;
it is possible to run the program from a removable storage devices;
you can view a detailed log of all performed operations.