Subject: [bitcoin-dev] Emergency Deployment of SegWit as a partial mitigation of CVE-2017-9230

From: Cameron Garnham <[email-masked]>
Date: Fri, 26 May 2017 09:30:08 +0300

Hello Bitcoin-Dev,

CVE-2017-9230 (1) (2), or commonly known as ‘ASICBOOST’ is a severe (3) (4) and actively exploited (5) security vulnerability.
 
To learn more about this vulnerability please read Jeremy Rubin’s detailed report:
http://www.mit.edu/~jlrubin//public/pdfs/Asicboost.pdf
 
Andreas Antonopoulos has an excellent presentation on why asicboost is dangerous:
https://www.youtube.com/watch?v=t6jJDD2Aj8k

In decisions on the #bitcoin-core-dev IRC channel; It was proposed, without negative feedback, that SegWit be used as a partial-mitigation of CVE-2017-9230.

SegWit partially mitigates asicboost with the common reasonable assumption that any block that doesn’t include a witness commit in it's coinbase transaction was mined using covert asicboost.  Making the use of covert asicboost far more conspicuous.

It was also proposed that this partial mitigation should be quickly strengthened via another soft-fork that makes the inclusion of witness commits mandatory, without negative feedback.

The security trade-offs of deploying a partial-mitigation to CVE-2017-9230 quickly vs more slowly but more conservatively is under intense debate.  The author of this post has a strong preference to the swiftest viable option.

Cameron.

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

(2) Announcement of CVE to Mailing List:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014416.html

(3) Discussion of the perverse incentives created by 'ASICBOOST' by Ryan Grant:
 https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014352.html

(4) Discussion of ASICBOOST's non-independent PoW calculation by Tier Nolan:
 https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014351.html

(5) Evidence of Active Exploit by Gregory Maxwell:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-April/013996.html