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Re: heads-up for critical apt problem



+ apt list

Hi,
* Bjoern Jacke <bjoern@j3e.de> [2016-09-22 15:06]:
> On 22.09.2016 14:19, Nico Golde wrote:
> > Wouldn't a person being in charge to apply updates in the first place also 
> > notice this error and fix it?
> 
> as I have written in the bug report. The error message says explicitly
> that only that single repository will not work - which generally implies
> that other repositories will be unaffected.
> 
> A repository or mirror maintainer (I am one for example...) would be
> able right now to stop any update to be installed on their users'
> servers. Users would see a message that my (attacker) repository is
> "expired" but all the other repos are fine (including
> security.debian.org!). Then I would have time to hack them. From my
> server logs I would even see, who of the users did *not* disable my
> intentionally broken repository.
> 
> I might also time my attack better: I wait for some upstream project to
> report a serious remote exploit and THEN break by repository, so that
> server maintainers don't have much time to notice the error message that
> they have a broken repository. Users would not receive the updates for
> the just released security fixes.
> 
> Now that I pointed out how I might easily prepare attacks with this apt
> bug it look to me like a very obviously critical security flaw. This
> looks to me like one of those class of bugs which might have been
> implemented intentionally. I hope you see this the same way and push the
> apt maintainers to fix this as soon as possible.

Thanks a lot for your detailed thoughts on this, this definitely helps 
understanding you better. I have tagged the respective bug entry as a security 
bug based on the general understanding and agreeing that this can have 
security impact. I do not agree with regard of your applied rating (which is 
btw not reflected in the BTS) however for two reasons: apt itself is not a 
silver bullet for solving security problems, in the end it's administrators or 
automation behind these tools that needs to do the job; more importantly 
though, your rationale is based on assuming that it's a key aspect to a 
compromise to have more time.

This certainly helps in some situations, but the general rule of thumb is you 
need to apply updates as fast as possible, you should not do this blindly and 
if you do problems likely occur, and even then you can be unlucky as most of 
the fixed issues are not unknown at the time of the fix to the broader public.

This is not meant to shoot you down, I am eager to hear the response of the 
apt maintainers as well. Please stop speculating about the origin of an issue 
as this is not constructive and might also be taken as rude.

Kind regards,
Nico
-- 
Nico Golde - XMPP: nion@jabber.ccc.de - GPG: 0xA0A0AAAA

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