W3C home > Mailing lists > Public > public-webappsec@w3.org > February 2016

Re: Proposal to add a browsing context named "_private"

From: Utkarsh Upadhyay <musically.ut@gmail.com>
Date: Sat, 6 Feb 2016 15:14:56 +0100
Message-ID: <CALh3q9xxQimp+9ZFU1rX1hTWJNr9hNKrhopYSPeAPEs_-D4=iw@mail.gmail.com>
To: Tanvi Vyas <tanvi@mozilla.com>
Cc: Crispin Cowan <crispin@microsoft.com>, Joel Weinberger <jww@chromium.org>, Anne van Kesteren <annevk@annevk.nl>, "timeless@gmail.com" <timeless@gmail.com>, Patrick Toomey <patrick.toomey@github.com>, Richard Barnes <rbarnes@mozilla.com>, WebAppSec WG <public-webappsec@w3.org>
Hi Tanvi,

Thanks for bringing the previous discussion to my notice. The crux, if I am
getting this right, was allowing websites to request the browser to open
them in Incognito mode via headers. This compliments links which have
target="_private" as the bowser can make use of both these hints. However,
the scope of these two suggestions is slightly different: while sending of
headers can be done when the user types in the URL himself,
target="_private" covers only cases when the referrer *thinks* that the
target website should be opened in incognito mode.

Other than that, they share similar problems and benefits: both can be
exploited for phishing attacks, both require (some) standardization of
private mode browsing, and both make the private mode feature more
discoverable.

Following the discussion here, I have come to believe that giving websites
ability to manipulate history in any way would be a Bad Idea (TM) and that
if a user runs into a handful of links which require permissions pop-ups
again and again, they would become annoying and will be ignored. I am still
undecided about domain-wide time-limited ask-once permissions to allow
private mode browsing.

Nevertheless, as someone who would use this feature, I am happy that there
is at least some interest in it. I hope that I was able to contribute a
different, albeit incomplete, solution. :)

~
ut



On Sat, Feb 6, 2016 at 2:41 AM, Tanvi Vyas <tanvi@mozilla.com> wrote:

> Something similar to this was discussed a few months ago on this list:
> https://lists.w3.org/Archives/Public/public-webappsec/2015Sep/0016.html
>
> The biggest issue I see is that this could be easily abused by
> phishing/malware sites.
>
> The proposal considered sites that tailored towards victims of domestic
> abuse.  But if the victim found the page through a search engine, the
> search terms would still be in their history.  And hence opening the abuse
> site in a private window may give victims a false sense of security.  A web
> API that caused the browser to ask the user if they wanted to clear that
> last X minutes of their history may be more useful.
>
> ~Tanvi
>
> On 1/24/16 2:03 AM, Utkarsh Upadhyay wrote:
>
> So here's a summary of the discussion so far (the status of items with
> question mark is not completely clear to me):
>
> Proposal: adding target="_private" to <a> tag spec and an explicit
> "private mode" browsing context.
>
> Pros:
>   + Better UI/UX on some sites (e.g. some links on Reddit).
>   + Easier to give instructions when sites require a session/cookie-less
> browsing context.
>   + Easier discoverability of the private browsing feature.
>
> Cons:
>   - Sites may conduct (phishing?) attacks on the user and not leave a
> trace.
>   - Whether to go private or not should be strictly a user decision.
>   ? Will require standardizing Incognito/private mode across browsers.
>   - Unclear how to explain the risks involved in simple language to the
> user.
>
> Compromises:
>   - Pop-ups for each click: too annoying and will be ignored.
>   ? One-off permission for domains, like the permissions for media access.
>
> Did I miss anything?
>
> ~
> ut
>
>
> On Thu, Jan 14, 2016 at 2:29 AM, Crispin Cowan <crispin@microsoft.com>
> wrote:
>
>> I basically disbelieve the premise of the idea. Whether any particular
>> web browsing should be privatized/not-logged is not the web site’s
>> business, that is a user decision.
>>
>>
>>
>> Regarding the prompt, I completely agree with Joel, that would become a
>> nuisance prompt that users don’t understand, and quickly come to hate and
>> ignore.
>>
>>
>>
>> *From:* Joel Weinberger [mailto:jww@chromium.org]
>> *Sent:* Wednesday, January 13, 2016 5:27 PM
>> *To:* Utkarsh Upadhyay < <musically.ut@gmail.com>musically.ut@gmail.com>;
>> Crispin Cowan <crispin@microsoft.com>
>> *Cc:* Anne van Kesteren < <annevk@annevk.nl>annevk@annevk.nl>;
>> timeless@gmail.com; Patrick Toomey <patrick.toomey@github.com>; Richard
>> Barnes <rbarnes@mozilla.com>; WebAppSec WG <public-webappsec@w3.org>
>>
>> *Subject:* Re: Proposal to add a browsing context named "_private"
>>
>>
>>
>> That is now something Chrome would do, in part because we believe it
>> wouldn't mitigate the risk. Users would become desnesitized and click
>> through anyway, but even more importantly, there's no way to explain the
>> attack in generally understandable terminology.
>>
>>
>>
>> On Wed, Jan 13, 2016, 4:01 PM Utkarsh Upadhyay < <musically.ut@gmail.com>
>> musically.ut@gmail.com> wrote:
>>
>> > Let me put this another way: the _private proposal is an attack
>> vector. It lets a malicious web site block the user’s browser from
>> recording history data without the user’s consent.
>>
>>
>>
>> What if we ask the user for consent before opening each link or make the
>> websites ask for user's permissions explicitly just like for media access?
>> Would that mitigate the security risk?
>>
>>
>>
>> ~
>>
>> ut
>>
>>
>>
>>
>>
>> On Tue, Jan 12, 2016 at 11:57 PM, Crispin Cowan < <crispin@microsoft.com>
>> crispin@microsoft.com> wrote:
>>
>> My comment about bookmarks was a joke: the point of private browsing is
>> to not leave tracks on your PC that you have browsed to a particular place.
>> Having a bookmark on your PC for “naughty salacious things” is itself an
>> obvious trace, and so defeats the purpose.
>>
>>
>>
>> Let me put this another way: the _private proposal is an attack vector.
>> It lets a malicious web site block the user’s browser from recording
>> history data without the user’s consent. If someone were to ship such a
>> feature in our browser, I would file a security bug to have it removed.
>>
>>
>>
>> *From:* Utkarsh Upadhyay [mailto: <musically.ut@gmail.com>
>> musically.ut@gmail.com]
>> *Sent:* Tuesday, January 12, 2016 2:38 AM
>> *To:* Anne van Kesteren < <annevk@annevk.nl>annevk@annevk.nl>
>> *Cc:* Crispin Cowan < <crispin@microsoft.com>crispin@microsoft.com>;
>> Joel Weinberger < <jww@chromium.org>jww@chromium.org>; timeless@gmail.com;
>> Patrick Toomey < <patrick.toomey@github.com>patrick.toomey@github.com>;
>> Richard Barnes < <rbarnes@mozilla.com>rbarnes@mozilla.com>; WebAppSec WG
>> < <public-webappsec@w3.org>public-webappsec@w3.org>
>> *Subject:* Re: Proposal to add a browsing context named "_private"
>>
>>
>>
>> > I know! How about letting the user specify that a bookmark should be
>> opened in-private? … oh, right :P
>>
>>
>>
>> I understand that the comment was made to show that target="_private"
>> will not solve all problems associated with opening links in private mode,
>> but this set me thinking in another direction.
>>
>> As Crispin's comment points out, bookmarking is also a feature common to
>> all browsers and which is, AFAIK, not standardized (notwithstanding the
>> link type="bookmark", which doesn't address this feature of browsers
>> explicitly).
>>
>> I don't see any immediate benefit of standardizing it and I actually
>> wouldn't support it without some very very good reasons.
>>
>>
>>
>> However, the more I think about it, private mode browsing is the kind of
>> feature which would really benefit from standardization: it would make the
>> developers know what to expect and would make sure that users get the
>> similar sort of guarantees across all conforming browsers.
>>
>> In that spirit, I think a new named browsing context is a good way to
>> introduce such a standardization and a way of opening it up to web
>> developers.
>>
>>
>>
>> ~
>>
>> ut
>>
>>
>>
>>
>>
>> On Tue, Jan 12, 2016 at 9:18 AM, Anne van Kesteren < <annevk@annevk.nl>
>> annevk@annevk.nl> wrote:
>>
>> On Tue, Jan 12, 2016 at 1:08 AM, Crispin Cowan < <crispin@microsoft.com>
>> crispin@microsoft.com> wrote:
>> > I think this whole area causes more problems than it solves. I can
>> clearly
>> > see the problems, much less clear on potential solutions, and really
>> vague
>> > on the problem it is trying to solve.
>>
>> It seems pretty clear to me. For some use cases, the website can offer
>> better UI than the browser. E.g., for most social media that relates
>> around sharing links, as OP suggested, the user could opt-in to
>> opening certain links in a "private mode". This is much more
>> discoverable than the equivalent feature in a browser and is also more
>> usable as you don't have to right-click, hold down a set of keys, or
>> some equivalent forgetful thing on your phone.
>>
>>
>> --
>> <https://annevankesteren.nl/>https://annevankesteren.nl/
>>
>>
>>
>>
>>
>>
>
>
Received on Saturday, 6 February 2016 14:15:45 UTC

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