Warren Kumari has entered the following ballot position for
draft-ietf-bess-srv6-services-10: Discuss

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DISCUSS:
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The Security Considerations section says: "The service flows between PE routers
using SRv6 SIDs advertised via BGP are expected to be limited within the
trusted SR domain (e.g., within a single AS or between multiple ASes within a
single provider network).  Precaution should be taken to ensure that the BGP
service information (including associated SRv6 SID) advertised via BGP sessions
are limited to peers within this trusted SR domain." This is related to (from
RFC8402): "Therefore, by default, the explicit routing information MUST NOT be
leaked through the boundaries of the administered domain."

However, we all know that BGP leaks happen -- and when they do, the SID’s
contained in the leak will be logged by various systems and hence available to
the public into perpetuity.

While the document states that border filtering should protect against traffic
injection, this does not cover the case of internal compromise. Sure, there is
the argument that once there is an internally compromised system, all bets are
off -- but with this, an attacker that knows the SIDs in e.g inject traffic
into a VPN. This seems to me to significantly expand the attack surface to
include the customer's networks too.

Not only does an operator have to ensure that BGP leaks never occur, they have
to then ensure that at no point can there be any filter lapses at any border
node, and be able to guarantee the security of every device, server and machine
within the domain in order for a secure posture to be maintained. Simply saying
that precautions should be taken to make sure that route leak don't occur, when
the consequences of doing so are a: severe and b: hard to recover from seems to
not really cover it. In addition, it seems that the blast radius from a missing
ACL seems much larger if it allows injections.


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COMMENT:
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I'm still reviewing the document, but wanted to get an initial ballot in, so
that we could start discussing it. Hopefully someone can help my understand how
this doesn't expand the consequences of a BGP leak.



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