[inline responses]On Thu, Sep 14, 2017 at 2:27 PM, Anthony Towns via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org > wrote:On Tue, Sep 12, 2017 at 09:10:18AM -0700, Simon Liu wrote:
> It would be a good starting point if the current policy could be
> clarified, so everyone is on the same page, and there is no confusion.
Collecting various commentary from here and reddit, I think current de
facto policy is something like:
* Vulnerabilities should be reported via security@bitcoincore.org [0]
* A critical issue (that can be exploited immediately or is already
being exploited causing large harm) will be dealt with by:
* a released patch ASAP
* wide notification of the need to upgrade (or to disable affected
systems)
* minimal disclosure of the actual problem, to delay attacks
[1] [2]
* A non-critical vulnerability (because it is difficult or expensive to
exploit) will be dealt with by:
* patch and review undertaken in the ordinary flow of development
* backport of a fix or workaround from master to the current
released version [2]
* Devs will attempt to ensure that publication of the fix does not
reveal the nature of the vulnerability by providing the proposed fix
to experienced devs who have not been informed of the vulnerability,
telling them that it fixes a vulnerability, and asking them to identify
the vulnerability. [2]
* Devs may recommend other bitcoin implementations adopt vulnerability
fixes prior to the fix being released and widely deployed, if they
can do so without revealing the vulnerability; eg, if the fix has
significant performance benefits that would justify its inclusion. [3]
* Prior to a vulnerability becoming public, devs will generally recommend
to friendly altcoin devs that they should catch up with fixes. But this
is only after the fixes are widely deployed in the bitcoin network. [4]
* Devs will generally not notify altcoin developers who have behaved
in a hostile manner (eg, using vulnerabilities to attack others, or
who violate embargoes). [5]
* Bitcoin devs won't disclose vulnerability details until >80% of bitcoin
nodes have deployed the fixes. Vulnerability discovers are encouraged
and requested to follow the same policy. [1] [6]
Those seem like pretty good policies to me, for what it's worth.
I advocate a policy like this, except I propose two modifications:- Point 4 should include *zero or more* altcoin developers, such that those altcoins also deploy mitigations as early as Bitcoin. (Call this "early altcoin disclosure".)- Disclose of vulnerabilities, by social convention, always explicitly names which altcoin developers were included in my proposed Early Altcoin Disclosure and Point 6.The rationale is that the policy should allow closer coordination with altcoins. If the goal is minimizing economic damage, including altcoins earlier may be the better trade-off between inclusiveness and secrecy. At the same time, the policy doesn't establish *which* altcoins, which is a tricky choice. However it *does* require disclosure of those relationships, which provides a form of feedback on the system.Imagine if altcoin X is compromised, and later disclosure occurs that reveals that altcoin X was not contacted early, then this *might* indicate leaks, maliciousness in the Bitcoin mitigation organization, or it *might* be coincidence or dumb luck. In the other case, if the Bitcoin disclosure reveals that X was indeed contacted early, then it probably indicates incompetence of the altoin X.Finally, notice that this kind of loose early disclosure policy can be symmetric. For example, Zcash developers may choose to disclose vulnerabilities they discover which affect Bitcoin to Bitcoin developers *before* Zcash releases fixes, or before those fixes are widely adopted in Zcash. We actually have a policy of doing this, since it's obvious that if our mitigation process leaks and that's used to attack Bitcoin the potential economic damage is very large.
I haven't seen anything that indicates bitcoin devs will *ever* encourage
public disclosure of vulnerabilities (as opposed to tolerating other
people publishing them [6]). So I'm guessing current de facto policy is
more along the lines of:
* Where possible, Bitcoin devs will never disclose vulnerabilities
publically while affected code may still be in use (including by
altcoins).
rather than something like:
* Bitcoin devs will disclose vulnerabilities publically after 99% of the
bitcoin network has upgraded [7], and fixes have been released for
at least 12 months.
I advocate for something like the latter case. I'd like to see a timeout on disclosure. There's an endless tail of alt-coins that could be affected, and no guarantee all will vigilantly upgrade. Meanwhile, deciding which of them to disclose to confidentially versus which should just receive hints to apply new patches is tricky and political.
Having a global timeout is a reasonable stop-gap. I consider the cost of never disclosing, publicly, a known vulnerbility to be very high, even if the fix is ubiquitously deployed, because it's a loss of security knowledge, a precious public good.
Instinctively, I'd say documenting this policy (or whatever it actually
is) would be good, and having all vulnerabilities get publically released
eventually would also be good; that's certainly the more "open source"
approach. But arguing the other side:
- documenting security policy gives attackers a better handle on where
to find weak points; this may be more harm than there is benefit to
improving legitimate users' understanding of and confidence in the
development process
Publishing a policy *might* increase organizational vulnerability, but so might *not publishing* a policy. It seems fairly neutral to me on vulnerability impact, whereas the benefit is good for users and developers.- the main benefit of public vulnerability disclosure is a better
working relationship with security researchers and perhaps better
understanding of what sort of bugs happen in practice in general;
but if most of your security research is effectively in house [6],
maybe those benefits aren't as great as the harm done by revealing
even old vulnerabilities to attackers
Publishing after a reasonable timeout has many benefits. Many security researchers learn from vulnerability disclosures across many disciplines and industries. Future protocol designers of things potentially unrelated to blockchain altogether may also learn important lessons.If the first of those arguments holds, well, hopefully this message has
egregious errors that no one will correct, or it will quickly get lost
in this list's archives...
Cheers,
aj
regards,Nathan WilcoxZcash[0] http://bitcoincore.org/en/contact
referenced from .github/ISSUE_TEMPLATE.md in git
[1] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017 -September/014986.html
[2] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017 -September/014990.html
[3] https://www.reddit.com/r/btc/comments/6zf1qo/peter_todd_nice ly_pulled_away_attention_from_ jjs/dmxcw70/
[4] https://www.reddit.com/r/btc/comments/6z827o/chris_jeffrey_j j_discloses_bitcoin_attack_vec tor/dmxdg83/
[5] https://www.reddit.com/r/btc/comments/6zb3lp/maxwell_admits_ core_sat_on_vulnerability/ dmv4y7g/
[6] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017 -September/014991.html
[7] Per http://luke.dashjr.org/programs/bitcoin/files/charts/branche s.html
it seems like 1.7% of the network is running known-vulnerable versions
0.8 and 0.9; but only 0.37% are running 0.10 or 0.11, so that might argue
revealing any vulnerabilities fixed since 0.12.0 would be fine...
(bitnodes.21.co doesn't seem to break down anything earlier than 0.12)
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