PwnageTool 4.2 will allow iPhone users to safely restore to a pre-jailbroken iOS 4.2.1 firmware and retain their current baseband so that they can use Ultrasn0w to unlock their GSM iPhone. PwnageTool 4.2 also includes fixes for iBooks issue that we had reported earlier and Wi-Fi problem on Apple TV 2G.
Dev Team has provided the following details in a blog post:
What’s in a name? Well in the case of an HFS volume name on iOS, an untether exploit — as the Chronic Dev Team revealed last week with an untether for the 4.2.1 jailbreak, which had previously been a tethered JB for most recent devices since 4.2.1’s release in November. With their permission, we’ve incorporated their 4.2.1 “feedface” untether into today’s PwnageTool 4.2. This means iPhone unlockers can safely restore to a custom 4.2.1 pre-jailbroken IPSW and retain their current baseband and unlock [..]
[..] PwnageTool also includes two very recent improvements to the 4.2.1 JB: iBooks was just fixed by @comex and @pushfix last night so that it works as intended on DRMed books, and the wifi problem on AppleTV 2G was fixed by @nitotv, @DHowett, and @saurik. Both of these fixes will also be available in upcoming Cydia package updates, so if you’re already jailbroken you can wait for those updates rather than restore and jailbreak again.
The various components to the 4.2.1 untether (including a second exploit involving Mach-o headers) were worked out by 0naj, posixninja, and pod2g, and a nice writeup by 0naj is available on the wiki. The actual injection method uses geohot’s limerain exploit for most devices.
PwnageTool 4.2 supports the following iOS devices for iOS 4.2.1:
Please note that jailbreaking your iDevice may void its warranty so proceed with caution and at your own risk. Please don’t forget to backup your iPhone before you proceed. You can refer to this post for instructions on how to backup your iPhone.
PwnageTool is available only for Mac users and you can download it from one of the mirror sites:
As always, please let us know how it goes and if you’re new to the jailbreaking world and wondering what to do after jailbreaking your iPhone, checkout our jailbreak apps category page to find out the apps you can install on your iPhone using the Cydia app, which is the App Store for jailbreak apps.
Windows users can checkout Sn0wbreeze 2.2 that has just been released by iH8sn0w.
Please note that Ultrasn0w 1.2 unlocks iPhone 4 baseband 01.59.00 and iPhone 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 and 06.15.00.
iPad and iPod Touch users are better off using Greenpois0n as you don’t need to preserve baseband like iPhone users and also assuming that the iBooks problem is a non-issue for you.[via Dev Team’s blog]