oss-sec mailing list archives

Re: CVE for Kali Linux


From: Daniel Micay <danielmicay () gmail com>
Date: Sun, 22 Mar 2015 23:58:06 -0400

On 22/03/15 03:23 PM, Stephen Kitt wrote:
On Sun, 22 Mar 2015 14:33:01 -0400, Daniel Micay <danielmicay () gmail com>
wrote:
[...]
At best, GPG offered *zero value* compared to checking a hash provided
via HTTPS, grabbing a torrent file via HTTPS or downloading directly via
HTTPS. However, I think it's pretty clear that few users would have gone
through with this and all it did was maintain the same security offered
by the HTTPS PKI.
[...]

I don't have any objection to the rest of your argumentation, which seems
sensible to me; at the very least it's clear that all this needs to be made
much easier, and (proper) HTTPS use should be encouraged.

But I do believe that *at best*, GPG offers something that HTTPS doesn't:
signature validation with peer-to-peer trust via the web of trust. This is
"at best" because most users don't have a key in the strong set; but at least
for Debian, the archive keys are in the strong set, so any one else with a
key in the strong set has at least one trust path to the archive key.

Of course that doesn't really help with the MITM scenario, since end users
would need to know that the archive key is supposed to be signed, and by
whom...

An attacker only needs control over a few keys in the strong set to add
any number of keys they want, which can then sign other keys. There's
value in the GPG WoT but it's non-trivial to extract it. You could
specifically find Debian devs and obtain their fingerprints securely
from various other places. I think the numbers of users who are going to
do this can probably be counted on a single hand. If there were actually
instructions on this in the installation guide, it could be argued that
a secure option is there.

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