In fact I was referring to the whole extension. OK, since you're forcing
my hand...
General
The mechanism must not reduce the security of IKEv2 or IPsec.
Specifically, an eavesdropper must not learn any non-public information
about the peers.
DoS Resistance
The proposed mechanism should be secure against attacks by a passive
MITM (eavesdropper). Such an attacker must not be able to disrupt an
existing IKE session, either by resetting the session or by introducing
significant delays.
The mechanism need not be similarly secure against an active MITM, since
this type of attacker is already able to disrupt IKE sessions.
Thanks,
Yaron
On 10/20/2010 03:58 PM, Yoav Nir wrote:
OK. I did not understand that this was about 5.2 rather than the whole
extension.
In that case, does section 10.4 address this? If not, can you suggest some
text?
Yoav
On Oct 20, 2010, at 3:47 PM, Yaron Sheffer wrote:
Hi Dave,
an active MITM, i.e. the sys admin at your local Starbucks, needs to
only drop a few packets of an open IKE SA (a few retransmissions) for
the peers to decide that they have a problem and attempt to renegotiate
the SA. This attack is trivial to mount if you're at the right spot.
On the other hand, Sec. 5.2 of the document is designed to prevent
another kind of DoS attack that eventually does the same thing: resets
the SA.
So we need to explain why we add a mechanism to prevent one kind of DoS
attacks even though we have other potential DoS issues. I'm not saying
this is wrong, I'm saying it needs to be rationalized.
Thanks,
Yaron
On 10/20/2010 02:57 PM, David Wierbowski wrote:
I'm not sure I understand Yaron's concern. Yaron, can you elaborate how a
MITM attacker can easily cause an IKE SA to be reset? I would think he
could only do so if he hi-jacked the original IKE_SA negotiation and is
now impersonating the remote security endpoint. In that case you have
bigger issues.
Dave Wierbowski
From: Yoav Nir<y...@checkpoint.com>
To: IPsecme WG<ipsec@ietf.org>
Date: 10/20/2010 04:10 AM
Subject: Re: [IPsec] Issue #194 - Security Considerations should discuss
the threat
Sent by: ipsec-boun...@ietf.org
One week, and no replies...
I will leave this issue open unless I get some suggested security
considerations text.
The first paragraph in section 10.1 says the following. What else is
missing?
Tokens MUST be hard to guess. This is critical, because if an
attacker can guess the token associated with an IKE SA, she can tear
down the IKE SA and associated tunnels at will. When the token is
delivered in the IKE_AUTH exchange, it is encrypted. When it is sent
again in an unprotected notification, it is not, but that is the last
time this token is ever used.
Yoav
On Oct 11, 2010, at 8:22 AM, Yoav Nir wrote:
Yaron: The security considerations are focused on details of the QCD
solution, rather then on the threats we are dealing with. These threats are
non-trivial to describe, since an active MITM attacker can easily cause an
IKE SA to be reset. OTOH, we don't want an active non-MITM attacker to be
able to do so. We need to analyze the threats in order to select a secure,
but not overly complex solution.
Suggested text would be most welcome.
Yoav
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