Qubes Security Bulletin #13 (also introducing Qubes Security Pack)

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Joanna Rutkowska

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Jan 5, 2015, 3:49:11 PM1/5/15
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Hello,

A new Qubes Security Bulletin has been just released and is available here:

https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-013-2015.txt

As per the previous discussions about recent problems with verifying
digital signatures on messages sent to Google Groups (thanks to
automatic footer addition by Google), we have decided to change the way
we publish Qubes Security Bulletins, as well as other security-related
info pertinent to the Qubes Project.

Starting today, we will be maintain a Git repository -- "Qubes Security
Pack" -- which will contain all the QSBs released so far, all the keys,
warrant canaries [1], and potentially some additional info or
announcements (e.g. key revocations). The whole repo can be found here:

https://github.com/QubesOS/qubes-secpack

Note that all the keys distributed there should be signed by Qubes
Master Key. The Master Key is also attached in the repo, but should
really be obtained/verified using a different channel.

Additionally, most of the files are signed by core Qubes
developers (currently by Marek and myself) via detached signatures as
well as git tag signatures.

The are several advantages of using Git to distribute all these information:

1) Git repo is a collection of files, some of which can be detached GPG
signatures for other files and we can ensure all these files are
distributed together.

2) Git makes it easy for people to clone and redistribute these
collection of files, as well as to easily host them and view on the Web.

3) Git provides for signed tags mechanisms which is another mean we
utilize to ensure integrity of the distributed files.

A few words about the Warrant Canary which we've just introduced today,
and which can be seen here:

https://github.com/QubesOS/qubes-secpack/blob/master/canaries/canary-001-2015.txt

Even though we're not providing any kind of services (such as e.g. email
hosting), that could be searched or tapped by authorities, there are
other possibilities that worry us [2], in the light of various recent
law "developments", such as those that might be coercing people to hand
over their private keys to authorities.

Until we fully decentralize the root of trust for Qubes, something that
requires the move to deterministic builds [3], and so won't happen
very soon, the possibility of having to disclose any of the Qubes
signing keys to anybody might have pretty serious consequences for those
who decided to entrust Qubes with anything serious. And we would like to
somehow minimize these consequences with this canary thing.

Additionally the canary is a nice way of ensuring "freshness" of our
messaging to the community.

Of course the canary doesn't solve all the problems. E.g. if my signing
keys were somehow stolen without our knowledge, it wouldn't help.
Neither it could help in case me being or becoming a miscreant. And
probably it doesn't address many other potential problems, which could
only be solved one day with a multi-signature scheme. But anyway, until
that time, this is the best we can do, I think.

And congrats to Jann for the very interesting clipboard attack (even
though mostly theoretical, still very cool)!

Thanks,
joanna.

--
The Qubes Security Team
http://wiki.qubes-os.org/trac/wiki/SecurityPage


[1] http://en.wikipedia.org/wiki/Warrant_canary

[2] Especially myself, because I'm currently the Root Of Trust for all
Qubes binaries :/

[3] Deterministic builds are required because it's the only way we can
implement multiple signature scheme for distributed binaries.


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