Vonage on iPhone

Vonage has promised to release an official iPhone app to compete with other providers such as Skype, and it is currently working its way through Apple’s well documented approval process. Unfortunately, this app would most likely come with an initial cost and/or subscription fee, though a way has been figured out to retrieve Vonage’s SIP authentication information, which would allow use of the Vonage network over other iPhone SIP Clients such as Fring. This solution does still contain the Wi-Fi only clause, but we have ways of making you talk, iPhone. This could also possibly be used on other platforms with SIP clients such as Android or WinMo.

25C3: Hacking the iPhone

As promised in their yellowsnow demo, [pytey], [MuscleNerd], and [planetbeing] from the iphone-dev team presented at 25C3 on their work Hacking the iPhone. The team originally formed in 2007 and this is the most comprehensive presentation on how the iPhone was compromised to date. You can find the full talk embedded above.

They opened with a few stats about how popular their software is. Our favorite by far is that at least 180 people with Apple corporate IPs update their phones using the dev-team’s software on a regular basis. From there the talk was split into two sections: jailbreaking the S5L application processor and unlocking the S-Gold baseband processor.

The phone relies on a chain of trust to guarantee that only Apple’s code is being run on it. All of userland is signature checked by the kernel. The kernel is checked when loaded by iboot. The iboot image is checked when loaded by LLB. LLB is loaded from the NOR by the lowest piece of code, the bootrom. That’s where things fall apart; the bootrom does not check the signature of the LLB. To take advantage of this, the team found what they describe as a classic stack buffer overflow in DFU mode. DFU is Device Firmware Upgrade mode, a state that the phone can be forced into after the bootrom loads. Their exploit forces the certificate check to return ‘true’. They are then able to patch all of the subsequent signature checks out of the phone’s system.

The baseband processor proved to be much more difficult simply because it doesn’t have any sort of recovery mode; bricking a phone was always a possibility. The S-Gold is a complete system-on-chip and has a unique ID on each phone. The NOR also has a unique ID on each phone. These two IDs are used to sign the secpack, which in turn enforces the SIM carrier lock. These unique IDs are why you can’t just take an officially unlocked phone and copy the secpack off of it to unlock another phone. Everything else is identical: the firmware, the baseband, the bootroom are all the same. On the second generation iPhone, the bootrom checks the bootloader. The bootloader then verifies the bootrom before checking and then loading the firmware. The firmware enforces the carrier lock. The team decided that it wasn’t worth attempting to break the chain of trust. The SIM unlock code they developed is divided into two sections. The first part is the actual software unlock. They patch the firmware while it’s running in RAM. Their patch modifies the firmware’s decision tree about whether to enforce the carrier lock. The second half is the exploit that allows them to inject the code. The team knows that Apple can and probably will patch the exploit hole, but their RAM patching code will always work, so it’s just a matter of finding another hole to apply it through. In order to do a permanent unlock solution (like on the first generation iPhone), they’d need to analyze the actual bootrom code.

The team mentioned several things Apple did that actually helped them in their efforts. Security was gradually rolled out, so they were able to look at things that would eventually be hidden. The firmware was initially unencrypted. Earlier versions trusted iTunes, something they could easily modify. All userland apps originally ran as root meaning any application exploit gave root level access.

The iphone-dev team has truly put in a tremendous amount of effort and we look forward to the yellowsn0w release on New Year’s Eve.

iPhone Linux

iPhone Linux Demonstration Video from planetbeing on Vimeo.

Embedded above is a demo video of an iPhone running a Linux 2.6 kernel. The iphone-dev team has created a new bootloader called OpeniBoot. The bootloader lets you boot into a Linux console, which you can talk to over a USB serial device. They’ve got busybox working, but there is no touchscreen support yet. The instructions are not that difficult and include how to back up your settings. It works on first and second gen iPhones and first gen iPod Touch. This is a very early port, but the future is wide open… Android iPhone?

iPhone 3G unlock video

To appease people waiting for the iPhone 3G unlock, iphone-dev team member [MuscleNerd] did a live video demo this afternoon. The video shows him removing the AT&T SIM and putting in a T-Mobile SIM. After the switch, the phone shows no connectivity. He then runs “yellosn0w” in an SSH session with the phone. The phone then unlocks without needing to be rebooted and the signal bars appear. The final test shows the phone receiving a call.

The target for this release is New Year’s Eve and it doesn’t support the most recent baseband. Well be attending the 25C3 talk hosted by [MuscleNerd] and other team members. The VNC screen you see in the video is thanks to [saurik]’s Veency.

iPhone 3G unlock released

As promised, the iphone-dev team has released yellowsn0w. You can install/uninstall via Cydia. It works fine with the latest firmware too. This sentence is filler.