Re: [websec] HSTS: Infinite max-age to address NTP spoofing attack?

"Hodges, Jeff" <> Mon, 10 November 2014 19:03 UTC

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From: "Hodges, Jeff" <>
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Thread-Topic: [websec] HSTS: Infinite max-age to address NTP spoofing attack?
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Date: Mon, 10 Nov 2014 19:03:01 +0000
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Subject: Re: [websec] HSTS: Infinite max-age to address NTP spoofing attack?
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On 11/7/14, 7:14 AM, "Hanno Böck" <> wrote:

>But I am pretty sure that no matter what, the underlying cause needs to
>be fixed. 

Strongly agreed.

>A reliable time plays a role in a number of cases in TLS.
>HPKP is basically vulnerable to the same kind of attack. Certificate
>validity times/expirations are vulnerable.

Yes, there's a plethora of protocols that contain timestampes of one sort
or another. Thus to some degree or another, they rely upo systems' time,
and if that time is corrupted by an attacker then the system and its users
may be in trouble. 

I don't think it's feasible, or in all or most cases a good design, to go
back and 'patch' those protocols to try to guard against NTP-based attacks
(as one example of how system time may be corrupted), rather, platforms
should (as AGL noted in a earlier thread "NTP vs. HSTS" on [1]) "fix the
clock" (I.e. Address NTP and other clock vulns).


[1] W3C Web App Security WG <>