New Kindle Fires are locked

kinfauns · Sep 14, 2012

I've exchanged several PMs with pokey9000 today. He has taken a look at the software update packages for both the 2nd generation KF and the 7" HD. The MLO (xloader, 1st stage bootloader) is signed and the boot header is the type used for HS (high security) OMAP devices with the M-Shield turned on. If the setup is comparable to the Nook Tablet, this is not good news for those hoping to modify these devices in one way or another. The Nook Tablet's exploit was to utilize the external sdcard as an alternate boot device and that doesn't really help with these 2nd generation KFs.

It's all subject to verification by someone who has a device in hand, but it doesn't look good. This is not to say that it's impossible, but it will be considerably more difficult to manipulate these devices than their 1st generation cousin.

So, let's all hope for the best, but be prepared for the worst. If you plan to buy one of these devices, buy them as an Amazon tablet to be used in the Kindle Fire ecosystem. Don't buy them expecting to run Jelly Bean the day after tomorrow.

fattire · Sep 14, 2012

Some clarification... and much left unanswered...

kinfauns said:
The Nook Tablet's exploit was to utilize the external sdcard as an alternate boot device and that doesn't really help with these 2nd generation KFs.

Not quite right. NT's exploit was far more complicated than that and has nothing to do with using the external SD card (or depending on one). It could have been done simply with root (or any other method for overwriting a partition, which was required to insert a 2nd unsigned bootloader into the boot sequence). If you're curious, you can look at the CyanoBoot 2nd bootloader for NT description or source to see what's going on.

I've taken a VERY quick look at the bootloader source for the HD7 as well, pushed here for anyone who wants it. There is in fact signature verification code in the uboot source (~line 140).

Also, looks like there are three configs-- bowser, jem, and tate. I have to look at it closer but it looks like tate is a subtype of bowser, and the HD7 I assume is tate. Hashcode also found a "radley" in the kernel code, but I haven't looked at that.

Anyway.. it is possible that bauwks' flaw or some other flaw exists in this signature verification code, but the code isn't identical to NT so who knows.

Incidentally, the new revision of the Kindle Fire (otter2) also has the same code, and there's a thread about the signature issue here as well.

It's all subject to verification by someone who has a device in hand, but it doesn't look good. This is not to say that it's impossible, but it will be considerably more difficult to manipulate these devices than their 1st generation cousin.

So, let's all hope for the best, but be prepared for the worst. If you plan to buy one of these devices, buy them as an Amazon tablet to be used in the Kindle Fire ecosystem. Don't buy them expecting to run Jelly Bean the day after tomorrow.

Yeah.. it all depends on whether there's a flaw as there was with the Nook Tablet... someone get bauwks on the line

Meanwhile, I'm enjoying my free (as in speech) Nexus 7...

pokey9000 · Sep 14, 2012

fattire said:
Not quite right. NT's exploit was far more complicated than that and has nothing to do with using the external SD card (or depending on one). It could have been done simply with root (or any other method for overwriting a partition, which was required to insert a 2nd unsigned bootloader into the boot sequence).

Technically true, but altering the boot chain with a removable microSD makes it a reversible process. Overwriting the boot image on emmc without any other boot options is serious brown trousers time. Now if they left in fastboot, then its not so scary if a similar hack to the NT can be done. Still, with no possibility of USB boot there's no recourse if any exploits get patched.

Meanwhile, I'm enjoying my free (as in speech) Nexus 7...

Yes.

Sent from my Nexus 7 using xda premium

kinfauns · Sep 14, 2012

fattire said:
Not quite right. NT's exploit was far more complicated than that and has nothing to do with using the external SD card (or depending on one). It could have been done simply with root (or any other method for overwriting a partition, which was required to insert a 2nd unsigned bootloader into the boot sequence). If you're curious, you can look at the CyanoBoot 2nd bootloader for NT description or source to see what's going on.

...

Thanks for the clarification and your input as well. I just wanted to get the discussions going on the possibilities of opening up this device to development, but also temper some expectations. There are many people waiting and some undoubtedly have ordered with the assumption that these 2nd generation devices will be getting the full range of development enjoyed by the original. I was mostly paraphrasing and summarizing, so I'll leave the details to those with the know-how.

I'm sure many people will be scouring the code and tinkering with their new devices in the coming days to figure something out.

fattire · Sep 15, 2012

Boring stuff...

pokey9000 said:
Technically true, but altering the boot chain with a removable microSD makes it a reversible process. Overwriting the boot image on emmc without any other boot options is serious brown trousers time

It's not THAT risky, I don't think. Even w/o SD card on NT, the safe(st) way to do it would be to replace the recovery partition with a 2ndboot/cyanoboot-enhanced recovery.img from a normal rooted boot. If recovery fails, you're still okay-- you can always just boot normally, gain root, and replace recovery again. If you're verified good, then use recovery to replace boot.img.

On NT, the normal secure boot sequence is unaffected when you replace recovery. That's because on the NT, you are never removing or touching the original uboot (ub1), so there's not much danger of a brick as long as you always have two means for booting (normal + recovery).

This is all academic as far as KFire HD goes, as I'm guessing from existence of the "crypto" partition that bauwks' bugfix won't work. I need to give a look at the signature verification stuff, as I haven't looked at it yet, but I'm not particularly optimistic.

pokey9000 said:
Now if they left in fastboot, then its not so scary if a similar hack to the NT can be done. Still, with no possibility of USB boot there's no recourse if any exploits get patched.

True, although w/NT, BN can only patch it by modifying the hardware, which would create massive support headaches for two versions of the boot. This is because w/unchanged hardware, the current, signed xloader->ub1->ub2 chain can always be used to load whatever. Again, I have more clarification on this-- if you're not already familiar with the details, find me on IRC.

speaking of fastboot, apparently if CONFIG_MACH_BOWSER_SUBTYPE_TATE is set, fastboot_idme is defined and fastboot and other debugging stuff seems to be turned on. I'm pretty sure "idme" is a uboot command. It's commented-out of drivers/fastboot.c as a shortcut to be enabled for TATE only.

FWIW, here are some various versions of the bowser board:

Bowser-Jem-PreEVT2-
Bowser-Jem-PreEVT2-
Bowser-Tate-PreEVT2.1-
Bowser-Tate-PostEVT2.1-
Bowser-Tate-PostEVT3HS2-
Bowser-Tate-DVT-
Bowser-Tate-PVT-
Bowser-Radley-

tate = product id 7
jem = product id 8
radley = product id 9
HS is High Security, I'm pretty sure.

Someone apparently is a fan of To Kill a Mockingbird (Boo Radley, Atticuls "Jem" Finch, Heck Tate, etc.). I don't know what the Bowser connection is... this guy? Or maybe just one of these.

Gotta go.

bournezhang · Sep 16, 2012

software RD of AMAZON said it was impossible to crack the NEW KF system, unless u know the key in the machine

wrexus · Sep 16, 2012

This was probably done in response to all the bricked Kindle Fires that were returned with the original Fire. That and the fact that if they didn't, it probably would have meant a price increase due to increased warranty expense. However, it seems i would make sense to simply allow an owner to pay a small fee to unlock the boot loader and register a modified Fire as "no warranty" for software issues.

psomero · Sep 17, 2012

kinfauns said:
I've exchanged several PMs with pokey9000 today. He has taken a look at the software update packages for both the 2nd generation KF and the 7" HD. The MLO (xloader, 1st stage bootloader) is signed and the boot header is the type used for HS (high security) OMAP devices with the M-Shield turned on. If the setup is comparable to the Nook Tablet, this is not good news for those hoping to modify these devices in one way or another. The Nook Tablet's exploit was to utilize the external sdcard as an alternate boot device and that doesn't really help with these 2nd generation KFs.

It's all subject to verification by someone who has a device in hand, but it doesn't look good. This is not to say that it's impossible, but it will be considerably more difficult to manipulate these devices than their 1st generation cousin.

So, let's all hope for the best, but be prepared for the worst. If you plan to buy one of these devices, buy them as an Amazon tablet to be used in the Kindle Fire ecosystem. Don't buy them expecting to run Jelly Bean the day after tomorrow.

I got my 7" Fire HD in the mail yesterday and am in this 100% to see custom roms running on it.

While I have just under a year of Android tinkering under my belt and many more years of experience playing with pc's and various flavors of embedded systems, I dunno where it all begins for this new device, but I want to help the dev community in any way I can.

If anybody has specific requests about the device or needs to test out something on one, I don't mind being a guinea pig, as long as there isn't too much risk of bricking my cool new toy...

deeper-blue · Sep 17, 2012

I will take a look at the u-boot sources of the new fires too and see how/what they have changed. Very possible that they fixed the funny flaw in the loading process for this iteration of their devices.
It would certainly be sad since a full HD android tab is tempting. At least for the 7inch category we have the nexus7 as an extremely good alternative.

thebrave · Sep 17, 2012

Ifixit has a teardown of the device, and there is a big test point labeled "USB BOOT" on the main board, and two smaller ones labeled "RX" and "TX"....

http://guide-images.ifixit.net/igi/UapMeZFPXthjTrEn.huge

JaxDomino · Sep 17, 2012

Returned

I have already hit the Return Item button on this. I could care less about the speakers and the screen! Gonna pick up the Nexus 7 instead.

bournezhang · Sep 17, 2012

pokey9000 said:
Technically true, but altering the boot chain with a removable microSD makes it a reversible process. Overwriting the boot image on emmc without any other boot options is serious brown trousers time. Now if they left in fastboot, then its not so scary if a similar hack to the NT can be done. Still, with no possibility of USB boot there's no recourse if any exploits get patched.

Yes.

Sent from my Nexus 7 using xda premium

just wait for pokey9000 to answer ， wait for u have idea how to USB boot it

robertc88 · Sep 17, 2012

psomero said:
I got my 7" Fire HD in the mail yesterday and am in this 100% to see custom roms running on it.

While I have just under a year of Android tinkering under my belt and many more years of experience playing with pc's and various flavors of embedded systems, I dunno where it all begins for this new device, but I want to help the dev community in any way I can.

If anybody has specific requests about the device or needs to test out something on one, I don't mind being a guinea pig, as long as there isn't too much risk of bricking my cool new toy...

Well I for one will be quite happy if someone can get an alternate launcher to work without rooting. Didn't have to on the original KF for them to work.

---------- Post added at 12:50 PM ---------- Previous post was at 12:46 PM ----------

JaxDomino said:
I have already hit the Return Item button on this. I could care less about the speakers and the screen! Gonna pick up the Nexus 7 instead.

I hope not cause the Nexus 7 for those two things ain't as good as this Fire HD.

DrWowe · Sep 18, 2012

Worst case scenario, there's always the kexec option. As a last resort, it works even on devices where the bootloader was never cracked.

ZilverZurfarn · Sep 18, 2012

robertc88 said:
Well I for one will be quite happy if someone can get an alternate launcher to work without rooting..

Yes, that would do it for me too (along with some ability to sideload apps). I preordered the 8.9 HD so I'll keep close watch on the development. If no solution is found before end of November, I just might cancel, and look around for what's hot (and rootable) at that point.

pokey9000 · Sep 18, 2012

bournezhang said:
just wait for pokey9000 to answer ， wait for u have idea how to USB boot it

USB boot needs a special boot loader (aboot in omap4boot used in Firekit) , and at least on the Nook Tablet it needs to be signed too. I doubt that TI's customers can or would opt for locking just flash boot so I'm going to assume that it won't work on the new Fires without a signed USB loader.

smirkis · Sep 18, 2012

glad to see everyone brainstorming over here. sorry for the bad news. i'm gonna follow these closely as i want to get a kfire hd for the gf eventually, but only when this bootloader gets unlocked. til then, back over to my n7 (which i find boring at times, because everything just works... bummer) lol

Loglud · Sep 20, 2012

fattire said:
It's not THAT risky, I don't think. Even w/o SD card on NT, the safe(st) way to do it would be to replace the recovery partition with a 2ndboot/cyanoboot-enhanced recovery.img from a normal rooted boot. If recovery fails, you're still okay-- you can always just boot normally, gain root, and replace recovery again. If you're verified good, then use recovery to replace boot.img.

On NT, the normal secure boot sequence is unaffected when you replace recovery. That's because on the NT, you are never removing or touching the original uboot (ub1), so there's not much danger of a brick as long as you always have two means for booting (normal + recovery).

This is all academic as far as KFire HD goes, as I'm guessing from existence of the "crypto" partition that bauwks' bugfix won't work. I need to give a look at the signature verification stuff, as I haven't looked at it yet, but I'm not particularly optimistic.

True, although w/NT, BN can only patch it by modifying the hardware, which would create massive support headaches for two versions of the boot. This is because w/unchanged hardware, the current, signed xloader->ub1->ub2 chain can always be used to load whatever. Again, I have more clarification on this-- if you're not already familiar with the details, find me on IRC.

speaking of fastboot, apparently if CONFIG_MACH_BOWSER_SUBTYPE_TATE is set, fastboot_idme is defined and fastboot and other debugging stuff seems to be turned on. I'm pretty sure "idme" is a uboot command. It's commented-out of drivers/fastboot.c as a shortcut to be enabled for TATE only.

FWIW, here are some various versions of the bowser board:

Bowser-Jem-PreEVT2-
Bowser-Jem-PreEVT2-
Bowser-Tate-PreEVT2.1-
Bowser-Tate-PostEVT2.1-
Bowser-Tate-PostEVT3HS2-
Bowser-Tate-DVT-
Bowser-Tate-PVT-
Bowser-Radley-

tate = product id 7
jem = product id 8
radley = product id 9
HS is High Security, I'm pretty sure.

Someone apparently is a fan of To Kill a Mockingbird (Boo Radley, Atticuls "Jem" Finch, Heck Tate, etc.). I don't know what the Bowser connection is... this guy? Or maybe just one of these.

Gotta go.

fattire is a beast for doing work on the Nooktablet with me, chm and all the other guys.... From what im reading, its actually kinda like booti from the Nook tablet. Very very interesting file at ./common/cmd_idme.c It seems as though theres a way to load a debugging kernel. Kinda curious if we can use that to smash a new boot into it. The following lines interest me:

./common/cmd_idme.c

Code:

#ifdef ENABLE_DIAG_KEY
        if (!val_vol_up && val_vol_down) {
                /* button up is pressed only */
                printf("Tablet: Enter dkernel mode: ....\n");
                *ptn = pdkernel;
        }

Code:

        case '2':
                printf("Select Diagnostic image\n");
                *ptn = pdkernel;
                break;

and also this line in the ./include/config/tate.h

Code:

#define CONFIG_DIAGNOSTIC_BOOTCOMMAND "mmcinit 1;mmc 1 read 0x580 0x81000000 0x600000; bootm 0x81000000"

As for the boot hole that bauwks discovered on the nook tablet, it is not on this device, though it is highly possible that if this Diagnostic mode can be activated we can use the same exploit as we used with the fatload and the booti. This CONFIG_DIAGNOSTIC_BOOTCOMMAND can maybe do the same thing with something in the SAR memory, so its worth someone doing somemore research.

adrian816 · Sep 20, 2012

thebrave said:
Ifixit has a teardown of the device, and there is a big test point labeled "USB BOOT" on the main board, and two smaller ones labeled "RX" and "TX"....

http://guide-images.ifixit.net/igi/UapMeZFPXthjTrEn.huge

One way to make the device harder to alter is by making these test points the physical connections for a bootloader USB port. Perhaps the USB port accessible to the user is solely intended as a data transfer port for multimedia where the driver is initialised only after the anti-hacking measures are loaded?

Entropy512 · Sep 20, 2012

pokey9000 said:
USB boot needs a special boot loader (aboot in omap4boot used in Firekit) , and at least on the Nook Tablet it needs to be signed too. I doubt that TI's customers can or would opt for locking just flash boot so I'm going to assume that it won't work on the new Fires without a signed USB loader.

This is standard operating practice. You can be assured that if flash boot is locked, USB boot will also be locked.

Interesting tidbit: While no Samsung Android device other than the Verizon GS3 (and rumor has it, upcoming Verizone Note 2) has a locked bootloader in terms of ability to boot a kernel, nearly ALL of them have the initial first stage of boot locked. It's just that Samsung usually drops the chain of trust early on. This is, for example, why Unbrickable Mod doesn't exist for any GS2 or GS3-family device - No one has access to a signed USB-bootable IBL/PBL/SBL setup. (Technically, one could likely USB-boot the existing IBL, but that IBL is hardcoded to go to flash for PBL/SBL.)

So far, no one I am aware of has ever compromised the low-level hardware enforcement of OMAP4 HS or Exynos4. In all cases of OMAP4, any compromise took advantage of holes in the chain of trust farther down the line - however nearly all attack vectors are known, so probably every compromise technique that is standard (kexec, second init, etc.) has a countermeasure in play with the KFHD if they're THAT confident in its unbreakability. In the case of Exynos4, in all current cases the chain of trust goes "insecure" so early that only people with clobbered bootloaders care.

New Kindle Fires are locked

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