Re: [rtcweb] Consent alternative

"Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com> Thu, 05 December 2013 04:43 UTC

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From: "Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com>
To: Martin Thomson <martin.thomson@gmail.com>
Thread-Topic: [rtcweb] Consent alternative
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Date: Thu, 5 Dec 2013 04:43:19 +0000
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References: <CABkgnnVNnT8uoWM8T=TqbTmy11CGTeHLP=_7z5KSMSpAsp9SyQ@mail.gmail.com> <52989933.6000907@ericsson.com> <CABkgnnUX3OFUyc5PXeN0ydykBwL0HyRuaigfJKMBbuWnuhnVJg@mail.gmail.com> <E721D8C6A2E1544DB2DEBC313AF54DE22436FBD9@xmb-rcd-x02.cisco.com> <CABkgnnUy3HxvsqYfwspEQ9_g1frUuFF4rwD-hTz45UzCr1fTBw@mail.gmail.com> <E721D8C6A2E1544DB2DEBC313AF54DE22437073A@xmb-rcd-x02.cisco.com> <CABkgnnVOuG9pNRA8RzBYOhTHUih0RASchVHxYsnYQk8fDs_VLA@mail.gmail.com> <E721D8C6A2E1544DB2DEBC313AF54DE224373610@xmb-rcd-x02.cisco.com> <CABkgnnUx_KfRYJ61_ymF_uXLs6o2NXka2gVG1a+K82YWBkF8CA@mail.gmail.com>
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Cc: "Cullen Jennings \(fluffy\)" <fluffy@cisco.com>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Consent alternative
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Apparently, we are talking about different problems. Perhaps, a diagram showing the sequence of steps that lead to the attack you are describing might help me understand it.

|-----Original Message-----
|From: Martin Thomson [mailto:martin.thomson@gmail.com]
|Sent: Thursday, December 05, 2013 12:08 AM
|To: Muthu Arul Mozhi Perumal (mperumal)
|Cc: rtcweb@ietf.org; Magnus Westerlund; Cullen Jennings (fluffy)
|Subject: Re: [rtcweb] Consent alternative
|
|On 3 December 2013 21:08, Muthu Arul Mozhi Perumal (mperumal)
|<mperumal@cisco.com> wrote:
|> |I think that you have missed the point here. The point is that A and
|> |B share a DTLS connection, and B uses ICE to convince A to send
|> |packets for that connection to C.
|>
|> Can you describe that in terms of a real-world use case? I don't see how that is different from a
|3PCC scenario where the 3PCC (e.g a call center agent) talks to both A and C, and transfers A to C
|(aka full-consult transfer).
|
|I'm not describing a use case, I'm describing an attack.  A 3PCC
|transfer should result in a new DTLS connection.  That's a completely
|different scenario.
|
|>
|> |All this requires is that B is able to spoof the source address of
|> |packets to appear as coming from C.
|>
|> B doesn't have to spoof anything at all -- for the ICE connectivity check to succeed b/w A and C, B
|just needs to send A's ice-ufrag and ice-pwd to C and vice versa.
|
|Yes, B does have to spoof something.  If B's goal is to cause A to
|send packets to C without consent from C (or, more precisely, even
|when C initially consents, then ceases to consent), then spoofing is
|necessary.