Combating records leaks by stripping direction records in HTTP Referrers

To support end third event records leakage whereas taking a glimpse privately, Firefox Personal Browsing Mode will decide away direction records from referrers sent to third parties starting in Firefox fifty 9.

Referrers can leak collected records

An instance of personal health records being sent to third parties from healthcare.gov. Offer: EFF

Whereas you occur to click on a link to your browser to navigate to a recent position, the recent position you talk over with receives the particular deal with of the position you came from thru the so-called “Referrer price”. For instance, in case you came to this Mozilla Security Blog from reddit.com, the browser would ship blog.mozilla.org this:

Referer: https://www.reddit.com/r/privacy/feedback/Preventing_data_leaks_by_stripping_path_information_in_HTTP_Referrers/

This leaks person records to web sites, telling web sites the particular web page you were taking a glimpse at if you occur to clicked the link. To make things worse, browsers also ship a referrer price when asking for sub-resources, delight in adverts, or just a few social media snippets constructed-in in a latest web position. In just a few phrases, embedded pronounce also knows precisely what web page you are visiting

Most sites log this records for operational and statistical applications. Many sites also log this records to build up as powerful records about their customers as possible.  They’ll then use that records for a range of applications, and even promote that records – e.g., for re-focused on.

Whereas the records above will no longer be an enviornment, take into story this instance:

Referer: https://www.
healthcare.gov/look for-plans/85601/results/?county=04019&age=40&smoker=1&pregnant=1&zip=85601&assert=AZ&earnings=35000

EFF researchers stumbled on this leak of personal health records from healthcare.gov to DoubleClick. As indicated, the referrer in this case leaks records about your age, your zip code, whether you are a smoker or no longer, and doubtlessly even your earnings. Completely different firms (link1, link2) bear disclosed identical vulnerabilities and leaks.

Personal Browsing will strip paths in HTTP referrers

To end this form of records leakage when Firefox customers are taking a glimpse privately, we are altering the formula Firefox sends referrers in Personal Browsing Mode.

Starting with Firefox fifty 9, Personal Browsing will decide away direction records from referrer values sent to third parties (i.e. technically, environment a Referrer Policy of strict-starting keep-when-pass-starting keep).

In the old examples, this environment would decide away the hurry and ask string records from the referrer values in allege that they are stripped all the draw in which down to:

Referer: https://www.reddit.com/

and

Referer: https://www.healthcare.gov/

This transformation prevents position authors from accidentally leaking person records to third parties when their customers spend Personal Browsing Mode.  We made this change only after first guaranteeing that this would bear minimal to no break on web usability.

Completely different ways of controlling referrers

Distributors and authors proceed to propose adjustments to Referrers to toughen web privacy, safety, and efficiency.

In 2014, the W3C Web Utility Security Working Neighborhood started its Referrer Policy Recommendation. This Policy lets vendors and authors adjust referrer values. For instance, it defines a stable-by-default no-referrer-when-downgrade policy for person brokers, which would no longer ship referrers to HTTP resources from an HTTPS web page. In Firefox Usual and Personal Browsing Mode, if a position particularly sets a more restrictive or more liberal Referrer Policy than the browser default, the browser will honor the web sites ask for the rationale that position creator is deliberately altering the worth.

Users will also change their default referrer choices in Firefox.  These will override the browser’s default Referrer Policy and override the position creator’s Referrer Policy, inserting the customers want first.