W3C home > Mailing lists > Public > public-webappsec@w3.org > April 2019

Re: Blocking high-risk non-secure downloads

From: Emily Stark <estark@google.com>
Date: Tue, 9 Apr 2019 12:36:17 -0700
Message-ID: <CAPP_2SaUtYninUs+GUXuOT=KQYKYuExamuMFoXwHyeOgHWxUsg@mail.gmail.com>
To: Michaela Merz <michaela.merz@rollofone.com>
Cc: WebAppSec WG <public-webappsec@w3.org>, Mike West <mkwst@google.com>, Joe DeBlasio <jdeblasio@chromium.org>, cthomp@chromium.org
On Tue, Apr 9, 2019 at 12:31 PM Michaela Merz <michaela.merz@rollofone.com>

> Here's a very problematic situation I am discussing with the Firebox
> people (and filed a bug report): Our application allows folks to assemble
> files, pack them into a zip and download the data. Some combination of
> certain files, when packed and zipped, seem to create a situation where
> Chromium (and Firefox) believe the data to be dangerous. I guess it's based
> on the signature. Chromium marks the download as potentially dangerous but
> allows the download anyway - Firefox however downloads the file and
> zero-truncates it on disk without any warning. Here's my point: The browser
> should never be allowed to discard or corrupt any data without the user's
> expressed knowledge. It is not enough to only have a tick-box in settings.
> Warnings need to be displayed on any potentially dangerous file. It is not
> acceptable when the browser decides by itself whether or not do allow
> downloads and doesn't tell the user. Signatures or other detection
> mechanism can (and as my case shows, will) deliver false positives and it's
> creating a slippery slope that may, at some point, be misused for other
> reasons. It is however - perfectly ok to warn the user and let him/her
> decide for themselves.

Hi Michaela, this sounds like an issue with the Safe Browsing download
protection feature, which is unrelated to blocking http downloads which
we're discussing in this thread. Please consider filing a bug at
https://crbug.com/new about this issue.

> Michaela
> On 4/9/19 1:28 PM, Emily Stark wrote:
> Hi webappsec friends,
> Over in Chrome land, we've been considering how to drive down non-secure
> downloads, particularly high-risk ones like executables. I wanted to see if
> other browsers would be interested in joining us on this adventure.
> We want to achieve the right balance between compatibility/user-disruption
> and security improvements, so we will likely start by treating certain
> high-risk downloads initiated from secure contexts as active mixed content
> and block them. We're still finalizing our metrics before we can share them
> publicly, but right now it's looking like it will be feasible to block a
> set of high-risk filetypes (executables and archives as determined by the
> Content-Type header or sniffed mime-type). We will likely focus on
> protecting desktop users because Android and Safe Browsing already provide
> protection
> <https://source.android.com/security/reports/Google_Android_Security_2018_Report_Final.pdf>
> against malicious APKs.
> We're not planning to focus on non-secure downloads initiated from
> non-secure contexts at the moment, because users at least see the "Not
> Secure" omnibox badge on those pages.
> Feedback welcome!
> Thanks,
> Emily
> --
> Email is unsafe. Send confidential text or data via
> packfrog: https://packfrog.com/biotope?ee=92d26b3152b13a508b88d5ee575143b
Received on Tuesday, 9 April 2019 19:36:54 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 18:55:06 UTC