Advisory: Amazon’s Silk Browser on the Kindle Didn’t Use SSL for Google Search

Overview

Amazon supplies the Silk Browser for their line of Kindle tablets. The browser includes a selection of three search engines, of which Google was setup without SSL. Furthermore, the browser prevented automatic redirection to the SSL version of Google’s main site when visiting it directly.

Details

Amazon provides the Silk browser, which is based on Google’s Chrome, for their line of Kindle Fire tablets. The Silk browser includes ability to select from three search engines (as shown in the screenshot below) – Google, Bing and Yahoo. Of these, when Google is selected, all searches¬† via the browser’s omnibox are done without HTTPS resulting in ability of malicious third parties to monitor user’s search engine traffic. Furthermore, going to “http://www.google.com” which normally would redirect to the SSL version, stayed in HTTP mode and prevented redirection. All other Google international domains (like google.ru, google.fr, etc) automatically redirected to the SSL versions.

The version we tested was v49.3.1, the vendor fixed the issue in v51.2.1. It is recommended that all users upgraded to the newest version of the Silk browser.

Screenshot_2016-07-21-08-39-43

Vendor Response

Other than a generic response we received initially, there has been no further communication from the vendor.

Credits

Bug discovered and advisory written by Yakov Shafranovich.

Timeline

2016-05-01: Both Amazon and Google notified via email
2016-05-02: Generic response from Amazon
2016-07-20: Verification of fix
2016-07-21: Public disclosure