Re: [bitcoin-dev] Treating ‘ASICBOOST’ as a Security Vulnerability

[Cameron Garnham <da2ce7@gmail.com>]

Hello Bitcoin-Dev,

A quick update that CVE-2017-9230 has been assigned for the security vulnerability commonly called ‘ASICBOOST’:

"The Bitcoin Proof-of-Work algorithm does not consider a certain attack methodology related to 80-byte block headers with a variety of initial 64-byte chunks followed by the same 16-byte chunk, multiple candidate root values ending with the same 4 bytes, and calculations involving sqrt numbers. This violates the security assumptions of (1) the choice of input, outside of the dedicated nonce area, fed into the Proof-of-Work function should not change its difficulty to evaluate and (2) every Proof-of-Work function execution should be independent.”

I would like to especially thank the CVE team at Mitre for their suggested description that was more appropriate than my proposed text.

https://cve.mitre.org/cgi-bin/cvename.cgi?name=+CVE-2017-9230

Cameron.



> Begin forwarded message:
> 
> From: <cve-request@mitre.org>
> Subject: Re: [scr-xxxxx] Bitcoin - All
> Date: 24 May 2017 at 18:52:22 GMT+3
> To: <da2ce7@gmail.com>
> Cc: <cve-request@mitre.org>
> 
> Signed PGP part
> > [Suggested description]
> > The Bitcoin Proof-of-Work algorithm does not consider a certain attack
> > methodology related to 80-byte block headers with a variety of initial
> > 64-byte chunks followed by the same 16-byte chunk, multiple candidate
> > root values ending with the same 4 bytes, and calculations involving
> > sqrt numbers. This violates the security assumptions of (1) the choice
> > of input, outside of the dedicated nonce area, fed into the
> > Proof-of-Work function should not change its difficulty to evaluate
> > and (2) every Proof-of-Work function execution should be independent.
> >
> > ------------------------------------------
> >
> > [Additional Information]
> > ASICBOOST, originality promoted as a patented mining optimisation(1).
> > Has under detailed study (2), become regarded as an actively exploited
> > (3), security vulnerability (4), of Bitcoin.
> >
> > The Bitcoin Proof-of-Work Algorithm is dependent on the following two
> > security assumptions that are both broken by 'ASICBOOST':
> > 1. The choice of input, outside of the dedicated nonce area, fed into
> > the Proof-of-Work function should not change it's difficulty to
> > evaluate.
> > 2.  Every Proof-of-Work function execution should be independent.
> >
> > 'ASICBOOST' creates a layer-violation where the structure of the input
> > outside of the dedicated nonce area will change the performance of the
> > mining calculations (5). 'ASICBOOST' exploits a vulnerability where
> > the Proof-of-Work function execution is not independent (6).
> >
> > References:
> > (1) Original Whitepaper by Dr. Timo Hanke: https://arxiv.org/ftp/arxiv/papers/1604/1604.00575.pdf
> > (2) Academic Write-up by Jeremy Rubin: http://www.mit.edu/~jlrubin//public/pdfs/Asicboost.pdf
> > (3) Evidence of Active Exploit by Gregory Maxwell:
> >  https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-April/013996.html
> > (4) Discussion to assign a CVE Number, by Cameron Garnham:
> >   https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014349.html
> > (5) Discussion of the perverse incentives created by 'ASICBOOST' by Ryan Grant:
> >   https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014352.html
> > (6) Discussion of ASICBOOST's non-independent PoW calculation by Tier Nolan:
> >   https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014351.html
> >
> > The patent holder of this particular security vulnerability has a dedicated website: https://www.asicboost.com/
> >
> > ------------------------------------------
> >
> > [VulnerabilityType Other]
> > Cryptocurrency Mining Algorithm Weakness
> >
> > ------------------------------------------
> >
> > [Vendor of Product]
> > Bitcoin
> >
> > ------------------------------------------
> >
> > [Affected Product Code Base]
> > Bitcoin - All
> >
> > ------------------------------------------
> >
> > [Affected Component]
> > Bitcoin
> >
> > ------------------------------------------
> >
> > [Attack Type Other]
> > Cryptocurrency Proof-of-Work Algorithm Weakness
> >
> > ------------------------------------------
> >
> > [CVE Impact Other]
> > Creation of Perverse Incentives in a Cryptocurrency
> >
> > ------------------------------------------
> >
> > [Attack Vectors]
> > Bitcoin Mining Unfair Advantage
> > Bitcoin Layer-Violations Creating Perverse System Incentives
> >
> > ------------------------------------------
> >
> > [Reference]
> > https://arxiv.org/ftp/arxiv/papers/1604/1604.00575.pdf
> > http://www.mit.edu/~jlrubin//public/pdfs/Asicboost.pdf
> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-April/013996.html
> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014349.html
> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014352.html
> > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014351.html
> >
> > ------------------------------------------
> >
> > [Has vendor confirmed or acknowledged the vulnerability?]
> > true
> >
> > ------------------------------------------
> >
> > [Discoverer]
> > Original Discovery: Dr. Timo Hanke and Sergio Lerner. Proof of Active
> > Exploit: Gregory Maxwell. CVE Reporter: Cameron Garnham
> 
> Use CVE-2017-9230.
> 
> 
> --
> CVE Assignment Team
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>