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Re: [TLS] [oss-security] CVE-2009-3555 for TLS renegotiation MITM attacks

Marsh Ray <marsh@extendedsubset.com> Sun, 08 November 2009 22:31 UTC

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Date: Sun, 08 Nov 2009 16:32:05 -0600
From: Marsh Ray <marsh@extendedsubset.com>
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To: ArkanoiD <ark@eltex.net>
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Cc: oss-security@lists.openwall.com, tls@ietf.org
Subject: Re: [TLS] [oss-security] CVE-2009-3555 for TLS renegotiation MITM attacks
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ArkanoiD wrote:
> BTW renegotiation handshake looks quite similar to initial handshake from
> the client point of view;

Yeah, currently it looks identical.

> is there a way to detect the attack on client side
> and drop the connection?

With draft-rescorla-tls-renegotiate, the new header comes back to the
client on Server Hello, and this notifies the client that the server
believes it's a re-negotation. Even better, it ties it strongly to the
previous session, so legit renegotiations are protected, too.

- Marsh

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