plea for comcast/sprint handoff debug help

Mon Nov 2 09:37:36 UTC 2020

On Mon, Nov 02, 2020 at 09:13:16AM +0100, Tim Bruijnzeels wrote:
> On the other hand, the fallback exposes a Malicious-in-the-Middle
> replay attack surface for 100% of the prefixes published using RRDP,
> 100% of the time. This allows attackers to prevent changes in ROAs to
> be seen.

This is a mischaracterization of what is going on. The implication of
what you say here is that RPKI cannot work reliably over RSYNC, which is
factually incorrect and an injustice to all existing RSYNC based
deployment. Your view on the security model seems to ignore the
existence of RPKI manifests and the use of CRLs, which exist exactly to
mitigate replays.

Up until 2 weeks ago Routintar indeed was not correctly validating RPKI
data, fortunately this has now been fixed:
https://mailman.nanog.org/pipermail/nanog/2020-October/210318.html

Also via the RRDP protocol old data be replayed, because because just
like RSYNC, the RRDP protocol does not have authentication. When RPKI
data is transported from Publication Point (RP) to Relying Party, the RP
cannot assume there was an unbroken 'chain of custody' and therefor has
to validate all the RPKI signatures.

For example, if a CDN is used to distribute RRDP data, the CDN is the
MITM (that is literally what CDNs are: reverse proxies, in the middle).
The CDN could accidentally serve up old (cached) content or misserve
current content (swap 2 filenames with each other).

> This is a tradeoff. I think that protecting against replay should be
> considered more important here, given the numbers and time to fix
> HTTPS issue.

The 'replay' issue you perceive is also present in RRDP. The RPKI is a
*deployed* system on the Internet and it is important for Routinator to
remain interopable with other non-nlnetlabs implementations.

Routinator not falling back to rsync does *not* offer a security
advantage, but does negatively impact our industry's ability to migrate
to RRDP. We are in 'phase 0' as described in Section 3 of
https://tools.ietf.org/html/draft-sidrops-bruijnzeels-deprecate-rsync

Regards,

Job