Re: [OAUTH-WG] New Version Notification for draft-fett-oauth-dpop-03.txt

Torsten Lodderstedt <torsten@lodderstedt.net> Mon, 25 November 2019 12:10 UTC

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From: Torsten Lodderstedt <torsten@lodderstedt.net>
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Date: Mon, 25 Nov 2019 13:09:58 +0100
In-Reply-To: <D3DF992C-88BB-428E-A539-140F7481F2EA@forgerock.com>
Cc: Dave Tonge <dave.tonge@momentumft.co.uk>, oauth <oauth@ietf.org>
To: Neil Madden <neil.madden@forgerock.com>
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Subject: Re: [OAUTH-WG] New Version Notification for draft-fett-oauth-dpop-03.txt
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Hi Neil, 

> On 25. Nov 2019, at 12:38, Neil Madden <neil.madden@forgerock.com> wrote:
> 
> But for web-based SPAs and so on, I'm not sure the cost/benefit trade off is really that good. The biggest threat for tokens being stolen/misused is still XSS, and DPoP does nothing to protect against that. It also doesn't protect against many other ways that tokens leak in browsers - e.g. if a token leaks in your browser history then the threat is that the attacker is physically using your device, in which case they also have access to your DPoP keys. In the cases like the Facebook breach, where highly automated mass compromise was achieved, I think we're lacking evidence that PoP would help there either.
> 
> The single most important thing we can do to protect web-based apps is to encourage the principle of least privilege. Every access token should be as tightly constrained as possible - in scope, in audience, and in expiry time. Ideally at the point of being issued ...

I tend to agree with your assessment. The simplest way with current OAuth is use of code+pkce+refresh tokens, narrowly scoped access tokens, and resource indicators to mint RS-specific, privilege restricted, short lived access tokens. 

Do you think we should spell this out in the SPA BCP?

best regards,
Torsten.