Raspberry Pi Pico cracks BitLocker in under a minute
- Reference: 1707319809
- News link: https://www.theregister.co.uk/2024/02/07/breaking_bitlocker_pi_pico/
- Source link:
The technique was published in a [1]YouTube video over the weekend and demonstrated how a Raspberry Pi Pico can be used to gain access to a BitLocker-secured device in under a minute, provided you have physical access to the device.
[2]Youtube Video
[3]
A Lenovo laptop was used in the video, posted by user stacksmashing, although other hardware will also be vulnerable. The technique also relies on having a Trusted Platform Module (TPM) separate from the CPU. In many cases, the two will be combined, in which case the technique shown cannot be used.
[4]
[5]
However, if get your hands on a similarly vulnerable device secured with BitLocker, gaining access to the encrypted storage appears embarrassingly simple. The crux of it is sniffing out the key to the device as it is passed from TPM to CPU. The key is helpfully not encrypted.
This particular laptop had connections that could be put to use alongside a custom connector to access the signals between chips. Stir in an analyzer running on the Raspberry Pi Pico and for less than $10 in components, you can get hold of the master key for the laptop hardware.
[6]Raspberry Pi on IPO plans: 'We want to be ready when the markets are ready'
[7]Techie resurrects teletext on a vintage BBC Master
[8]Eben Upton on Sinclair, Acorn, and the Raspberry Pi
[9]Raspberry Pi sizes up HAT+ spec for future hardware add-ons
Microsoft has long [10]accepted that such attacks are possible, although it describes them as a "targeted attack with plenty of time; the attacker opens the case, solder, and uses sophisticated hardware or software."
At less than a minute in the example, we'd dispute the "plenty of time" claim, and while the Raspberry Pi Pico is undoubtedly impressive for the price, at less than $10, the hardware spend is neither expensive nor specific.
[11]
If your hardware is vulnerable, mitigation can be achieved through the use of a PIN.
It's enough to send administrators scurrying to their inventory lists to check for hardware they would be forgiven for assuming had been safely encrypted.
As one wag observed: "Congratulations! You found the FBI's backdoor." ®
Get our [12]Tech Resources
[1] https://youtu.be/wTl4vEednkQ
[2] https://youtu.be/wTl4vEednkQ
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/research&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ZcO3OF7pPAZMXQUlFYXMEwAAAdA&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/research&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZcO3OF7pPAZMXQUlFYXMEwAAAdA&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[5] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/research&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZcO3OF7pPAZMXQUlFYXMEwAAAdA&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[6] https://www.theregister.com/2024/01/30/raspberry_pi_ipo/
[7] https://www.theregister.com/2024/01/30/resurrecting_teletext/
[8] https://www.theregister.com/2024/01/15/eben_upton_on_sinclair_acorn/
[9] https://www.theregister.com/2023/12/11/rpi_hat_plus_m2/
[10] https://learn.microsoft.com/en-gb/windows/security/operating-system-security/data-protection/bitlocker/countermeasures
[11] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/research&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZcO3OF7pPAZMXQUlFYXMEwAAAdA&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[12] https://whitepapers.theregister.com/
No, storing the key and the data together on the same device without requiring another separate form of input is the real failure.
Basically, Microsoft allowed violation of the "something you have and something you know " separation principle. And that is, when you think of it, an obvious backdoor.
To be fair to Microsoft (did I just say that), the issue is more a hardware design issue than a software one.
Its a bit like blaming the bank, because the secure parcel company through the check over the wall
Less than a minute?
It would take longer than that to get the covers off, let alone do any soldering!
Re: Less than a minute?
It's still quicker than typing in the BitLocker recovery key if you've locked your laptop
Re: Less than a minute?
No solder required, at least not at the time. He made a board with a set of spring-loaded contacts spaced for a set of pads on the back of the motherboard. That plugs into the Pi. He has to take the back of the laptop off and move a cover out of the way but then just needs to press the Pi/contacts assembly against the pads while it boots.
Re: Less than a minute?
Take that, Lenovo, for making the laptops easy to repair.
(I actually really appreciate it!)
Hurt Locker
A great film.
BitLocker…not so much.
A brilliant testament to analysis
Maybe a Bitlocked drive could resist anything up to brute force, but knowing the mechanism, finding out that the key was transmitted in the clear between CPU and TPM, that was the straw that broke the camel's back.
And it just goes to show : if you want something encrypted securely, it has to be 100% from start to finish. No gaps allowed.
And gaps are Borkzilla's specialty. Somebody devised the whole Bitlocker scheme, failed to encrypt comms between CPU and TPM and thought "this is Good Enough TM ".
Unfortunately, intelligent people are everywhere, and processing power is cheap nowadays. You've been found out.
Time to tighten your security, with all the inconveniences that entails.
Re: A brilliant testament to analysis
" Somebody devised the whole Bitlocker scheme, failed to encrypt comms between CPU and TPM and thought "this is Good EnoughTM". "
Probably did it and thought "hehe, no one in history has ever been as clever as me".
Remember kids, no matter how smart you think you are there will always be someone cleverer than you out there.
Re: A brilliant testament to analysis
Pretty sure in this instance, the fail is Lenovo's, however I intend to try this on a few other machines over the weekend.
What about LUKS
That relies on the secret being typed in to the console, which is then used to decrypt the key from a keystore block. Is the encryption good enough on that to keep a Pi Zero busy for a few hours?
Re: What about LUKS
You can do LUKS a lot of ways - including hardware tokens like yubikeys or similar. If you're going with good'ol "Type this password in at boot" then I have to assume it's as good (or bad) as any other purely password based approach. If you an automate feeding the password you can break it in an amount of time determined by the complexity of the password.
Re: What about LUKS
"That relies on the secret being typed in to the console, which is then used to decrypt the key from a keystore block. Is the encryption good enough on that to keep a Pi Zero busy for a few hours?"
Not the same use-case. In this case, BitLocker relies on a key stored in a chip that can be "easily" sniffed.
just out of curiosity - if you are going to buy a laptop what is the best way to find out if the CPU and TPM are on the same chip
"just out of curiosity - if you are going to buy a laptop what is the best way to find out if the CPU and TPM are on the same chip"
Download the datasheet from the vendor's website for that computer. Usually a PDF.
And I know people who wonder why on my own laptops I have PIN enabled on bitlocker - I just do not trust things that unlock automatically, just like I cannot fathom how MS think me having a silly little PIN is safer on mine, or a company laptop than me using a passphrase.
Hey ho
As a nice little demo to our cybersec guys, I kept a tally of how many user's laptops used 12345678 or some similarly obvious PIN.
They were quite upset.
It's nearly impossible to protect a device that someone else has physical access to. It has never worked trying to lock-down consumer electronic devices, and it never will.