Chntpw

chntpw is a software utility for resetting or blanking local passwords used by Windows NT, 2000, XP, Vista, 7, 8, 8.1 and 10. It does this by editing the SAM database where Windows stores password hashes.
Features.
There are two ways to use the program: via the standalone "chntpw" utility installed as a package available in most modern Linux distributions (e.g. Ubuntu) or via a bootable CD/USB image. There also was a floppy release, but its support has been dropped.
Limitations.
chntpw has no support for fully encrypted NTFS partitions (the only possible exceptions to this are encrypted partitions readable by Linux such as e.g. LUKS), usernames containing Unicode characters, or Active Directory passwords (with the exception of local users of systems that are members of an AD domain). The password changing feature also isn't fully functional either, so password blanking is highly recommended (in fact, for later versions of Windows that's the only possible option). Furthermore, the bootable image might have problems with controllers requiring 3rd party drivers. In such cases use of the stand-alone program in a full-featured Linux environment is recommended.
Where it is used.
The codice_1 utility is included in many various Linux distributions, including ones focused on security:
License change.
For the software's 10th anniversary, the author changed the license from a non-commercial one to the GNU General Public License (GPL) Version 2.