From nobody Tue Nov 3 11:14:08 2020 Return-Path: X-Original-To: oauth@ietfa.amsl.com Delivered-To: oauth@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2DEC93A010A for ; Tue, 3 Nov 2020 11:14:06 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.096 X-Spam-Level: X-Spam-Status: No, score=-2.096 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_FONT_LOW_CONTRAST=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0vv5-mzIFtzM for ; Tue, 3 Nov 2020 11:14:04 -0800 (PST) Received: from mail-lf1-x131.google.com (mail-lf1-x131.google.com [IPv6:2a00:1450:4864:20::131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 06F983A0100 for ; Tue, 3 Nov 2020 11:14:04 -0800 (PST) Received: by mail-lf1-x131.google.com with SMTP id h6so23727343lfj.3 for ; Tue, 03 Nov 2020 11:14:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3kZTwNbqU2LsGNzRSy3umbglKHE95RxrL3Q+baSOGwk=; b=eiWYuZ2M6MdDyo6tk2oYR/baAY5IIgFkpUx799Y00BbHcW8mvQwRiHls+E1aGotcsh zYiPupOmQgiKCiDwz7treLJdLJg7sHjFntNynvuCJf8b09iKjLbWJpKSmQlEQF+AMRPz 8UmQN9YmNnvjF6MyCmgMWwbTNktnpypYNkzWOa/UdTNOZYGcR3CjaA+4iKT/BNeklNv7 mXeyGWNEFoR7N8CHC3nq4e81j9ae0QhC5cHS1w6Ga8WXAd1Afcw9otK04gnXqO6IblzG BY0HWLE/jG3p/pdLet0035KozlryfVrVnBszLY1nX3HArWsURUREkeLvLwOp9uQH5UEC 1xHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3kZTwNbqU2LsGNzRSy3umbglKHE95RxrL3Q+baSOGwk=; b=Av4BGczovaJtVbahuw+CfOeuc/9Gl+7HTaPyxwoLPOusxPSkEQ4WpsfErpE0yYqsdl 1Q6Nt5RMBenApcySVKqKBeaTS4OqdOxkJTEB3VDq7VyGF2i2fV0gi+QMxJBTojwsPq8F K/NYB1j41+ZkGxZlB1DlMYBDQwI6qYjL12ThXYYkPLrH8atc57LGvWfghBdRuuc+uMPe cXFL+V7NCqQy0LFlW9eRgkak9CBSPADWJKWqZb3cQK+jlRYle1SdIYCET7QU4jlgk2iE Dhz1BmMC+FDeOrVdOgh4XKoZK3pI455N0tynO+9R4MDrgATXsj8t9XtM5VumZgszyxCn XWDA== X-Gm-Message-State: AOAM5319kwBi5gy5gpKm8Lel1wcmkeCeovCyUoVpMm6+y9oEE2dQbUMR HZHpHMTscndtlaHHjPW/RQAvFDZ0xudsZdmo6JU= X-Google-Smtp-Source: ABdhPJzpexYjeKRnb+51XM2QMoEqVq6Y4HAs/CFJVn1CuF3m7zS3HZaNkstJ7SGj0j4e7Ry97BpOD6WLATrB//xLkFc= X-Received: by 2002:a19:6b1a:: with SMTP id d26mr7705813lfa.162.1604430841982; Tue, 03 Nov 2020 11:14:01 -0800 (PST) MIME-Version: 1.0 References: <65B3EF09-25F4-4F3E-96DD-05FA60F044D0@authlete.com> In-Reply-To: <65B3EF09-25F4-4F3E-96DD-05FA60F044D0@authlete.com> From: Dick Hardt Date: Tue, 3 Nov 2020 11:13:26 -0800 Message-ID: To: Joseph Heenan , George Fletcher Cc: oauth Content-Type: multipart/alternative; boundary="0000000000006733cb05b338aa9b" Archived-At: Subject: Re: [OAUTH-WG] Android App Links (AKA Universal Links) X-BeenThere: oauth@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: OAUTH WG List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Nov 2020 19:14:06 -0000 --0000000000006733cb05b338aa9b Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Thanks Joseph. George Fletcher ran a great session on the topic at the last IIW as well. George: do you have a link? =E1=90=A7 On Tue, Nov 3, 2020 at 11:09 AM Joseph Heenan wrote: > Hi Dick > > I didn=E2=80=99t attend the call so don=E2=80=99t know the background of = this and the > exact situation, but the general problem is mostly where the Authorizatio= n > Server=E2=80=99s app is *not* installed. In that case Android falls back = to much > weaker mechanisms that allow other apps to get a look in. App links also > aren=E2=80=99t consistently supported across all commonly used android br= owsers > which causes further problems. > > In general to do app2app oauth redirections securely on Android it=E2=80= =99s > necessary for both apps to fetch the /.well-known/assetlinks.json for the > url they want to redirect to, and verify that the intent the app intends = to > launch to handle the url is signed using the expected certificate. Web2ap= p > flows are trickier, on both iOS and on Android. There were lengthy > discussions on at least the Android case at OAuth Security Workshop this > year (recordings available). > > Joseph > > > On 20 Oct 2020, at 00:09, Dick Hardt wrote: > > Hey Vittorio > > (cc'ing OAuth list as this was brought up in the office hours today) > > https://developer.android.com/training/app-links > > An app is the default handler and the developer has verified ownership of > the HTTPS URL. While a user can override the app being the default handle= r > in the system settings -- I don't see how a malicious app can be the > default setting. > > What am I missing? > > /Dick > =E1=90=A7 > _______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth > > > --0000000000006733cb05b338aa9b Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Thanks Joseph.

George Fletcher ran a gr= eat session on the topic at the last IIW as well.=C2=A0

George: do you have a link?

3D""=E1=90= =A7

On Tue, Nov 3, 2020 at 11:09 AM Joseph Heenan <joseph@authlete.com> wrote:
Hi Dick

I didn=E2=80=99t attend the call so do= n=E2=80=99t know the background of this and the exact situation, but the ge= neral problem is mostly where the Authorization Server=E2=80=99s app is *no= t* installed. In that case Android falls back to much weaker mechanisms tha= t allow other apps to get a look in. App links also aren=E2=80=99t consiste= ntly supported across all commonly used android browsers which causes furth= er problems.

In general to do app2app oauth redire= ctions securely on Android it=E2=80=99s necessary for both apps to fetch th= e /.well-known/assetlinks.json for the url they want to redirect to, and ve= rify that the intent the app intends to launch to handle the url is signed = using the expected certificate. Web2app flows are trickier, on both iOS and= on Android. There were lengthy discussions on at least the Android case at= OAuth Security Workshop this year (recordings available).

Joseph


On 20= Oct 2020, at 00:09, Dick Hardt <dick.hardt@gmail.com> wrote:

Hey Vittorio

(cc'ing OAuth list as this w= as brought up in the office hours today)


<= div>An app is the default handler and the developer has verified ownership = of the HTTPS URL. While a user can override the app being the default handl= er in the system settings -- I don't see how a malicious app can be the= default setting.

What am I missing?
/Dick
3D""=E1=90=A7
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