Crack Windows Administrator Passwords with Ophcrack

The Ophcrack Windows password cracker is one of the best, if not the very best free Windows password recovery tool available. It is fast and easy enough for a first time password cracker with a basic knowledge of Windows.

With Ophcrack, you don’t need any access to Windows to be able to recover your lost passwords. Simply visit the site, download the free ISO image, burn it to a CD and boot from it. The Ophrack program starts, locates the Windows user accounts, and proceeds to recover (crack) the passwords - all automatically.

I checked it personally on a customer computer, and Ophcrack recovered the 7-digit password to the administrator account in 95 seconds.

Ophcrack is an open source (GPL license) program that cracks Windows LM hashes using rainbow tables. The program includes the ability to import the hashes from a variety of formats, including dumping directly from the SAM files of Windows. The LiveCD version automates the retrieval, decryption, and cracking of passwords from a Windows system.

Rainbow tables for LM hashes of alphanumeric passwords are provided for free by the developers. These tables can crack 99.9% of alphanumeric passwords of up to 14 characters in usually a few seconds, and at most a few minutes. Starting with version 2.3, Ophcrack also cracks NT hashes. This is necessary if generation of the LM hash is disabled (this is default on Windows Vista), or if the password is longer than 14 characters (in which case the LM hash is not stored).

Using rainbow tables algorithm is responsible for speedy passwords recovery. The regular brute-force cracking tools typically try thousands of combinations of letters, numbers and special characters each second, but cracking a password by attempting every conceivable combination can take hours or days. Rainbow tables pre-computes the hashes used by passwords, allowing for a speedy password lookup by comparing the hashes it has, instead of computing them from scratch.

Thinking of it another way, someone else has already generated the password hashes for millions of potential passwords using the same algorithm as Windows XP and Vista. Ophcrack simply loads the megabytes of hashes it already has and compares the password hash in Windows against its giant database. When it finds a match, Ophcrack reveals the password in plain text.

Ophcrack is not malware and has its legitimate uses. For instance, most Windows password-recovery tools will substitute a new password in place of a lost one, but knowing the actual password may be useful in unlocking other archives found during a forensics investigation. Additionally, testing a known password against Ophcrack, and besting the rainbow tables, can help validate that the password is extremely strong.

MainFeatures:

» Runs on Windows, Linux/Unix, Mac OS X, ...
» Cracks LM and NTLM hashes.
» Free tables available for Windows XP and Vista.
» Brute-force module for simple passwords.
» LiveCD available to simplify the cracking.
» Loads hashes from encrypted SAM recovered from a Windows partition, Vista included.
» Free and open source software (GPL).

Pros and Cons

Pros

* Software is freely available for download online
* Passwords are recovered automatically using the LiveCD method
* No software installation is necessary to recover passwords
* No knowledge of any existing passwords is necessary
* Ophcrack works with Windows XP and Windows Vista

Cons

* 400MB+ (XP) / 500MB+ (Vista) LiveCD ISO image must be downloaded
* LiveCD ISO image must be burned to a CD before being used
* Some antivirus software may mistakenly flag Ophcrack as malware

Download the software from developer’s site: http://ophcrack.sourceforge.net/

The following video will assist you in the process of password recovery from the very beginning to the moment of getting desirable results.