Evasi0n is untethered jailbreak tool for all the supported devices running iOS 6 to iOS 6.1.2, excluding both Apple TV (3rd generation) revisions. This tool was released by evad3rs on 4th February 2013, and available for Windows, Mac OS X and Linux (x86 and x86_64). There is also a Cydia package called "evasi0n iOS 6.0-6.1.2 untether" which can untether an existing tethered jailbreak without the need to restore and use the desktop tool. It is a userland jailbreak.
Evasi0n 1.5.3 Download: