Re: [rtcweb] Consent alternative

"Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com> Thu, 05 December 2013 04:49 UTC

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From: "Muthu Arul Mozhi Perumal (mperumal)" <mperumal@cisco.com>
To: Martin Thomson <martin.thomson@gmail.com>, "Dan Wing (dwing)" <dwing@cisco.com>
Thread-Topic: [rtcweb] Consent alternative
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Date: Thu, 5 Dec 2013 04:48:55 +0000
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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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|-----Original Message-----
|From: rtcweb [mailto:rtcweb-bounces@ietf.org] On Behalf Of Martin Thomson
|Sent: Thursday, December 05, 2013 12:29 AM
|To: Dan Wing (dwing)
|Cc: Cullen Jennings (fluffy); rtcweb@ietf.org
|Subject: Re: [rtcweb] Consent alternative
|
|On 3 December 2013 16:24, Dan Wing <dwing@cisco.com> wrote:
|> Requiring sending an ICE request (and receiving an ICE response) would also _almost_ work -- that
|is, when remote party claims to change their IP address not only is an ICE request from their IP
|address needed, but also need to send an ICE request to their new IP address and get an ICE response
|(same as you are saying to send them a DTLS heartbeat to their new address).
|
|Yes, almost.  If ICE restart didn't also correspond with a change in
|ufrag/pwd it might.  As it stands, ICE restart and new victim look
|exactly the same.

RFC5245 section 9.1.1.1:
   To restart ICE, an agent MUST change both the ice-pwd and the ice-
   ufrag for the media stream in an offer.

Muthu

|
|> To thwart that, an ICE attacker would need to be on-path and we could envision places where B (the
|attacker in your enumerated list above) is on a shared network with C (victim), such as shared WiFi.
|
|In general, I find that on-path attackers aren't especially
|interesting when it comes to DoS attacks.  Shared WiFi seems like it
|might avoid the "directly on path" part, though since the attacker
|disadvantages themselves as much as their victim, I don't worry.
|
|> DTLS heartbeat prevents that attack because B (the attacker) doesn't know the necessary secrets to
|generate the DTLS heartbeat message (whereas with ICE, B would know the ICE username and ICE
|password).  If I have all that correct for how ICE consent could be attacked, it shows a security
|advantage of DTLS consent over ICE consent.
|
|Yes.  That is definitely an advantage.
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