On 6 Aug 2016 00:25:17 GMT, Jolly Roger wrote:

Does the exploit work in Safari?

In a quick read of these references...
https://www.theguardian.com/technolo...s-battery-life
http://www.independent.co.uk/life-st...-10435578.html
https://it.slashdot.org/story/15/08/...ack-you-online
http://www.wired.co.uk/article/privacy-hole-in-firefox
http://www.ibtimes.co.uk/smartphone-...xperts-1513979
http://mashable.com/2015/08/04/battery-privacy-html5/
http://www.telegraph.co.uk/technolog...-identity.html
http://www.belfasttelegraph.co.uk/te...-31423953.html
http://www.theinquirer.net/inquirer/...d-the-internet
http://blogs.wsj.com/digits/2015/08/...ow-to-stop-it/
http://eprint.iacr.org/2015/616.pdf
http://betanews.com/2015/08/03/priva...ck-you-online/
http://www.dailymail.co.uk/sciencete...web-users.html
http://www.repubblica.it/tecnologia/...ono-120471082/
http://www.liberation.fr/direct/elem...ouchard_14537/
http://tecnologia.elpais.com/tecnolo...07_043163.html
http://www.nzz.ch/nicht-nur-der-akku...nutzer-ld.1278
http://www.police.be/fed/fr/actualit...on-insoupconne
etc. (the last few are not in English though)

It seems it's "a little-known feature of the HTML5 specification" which
Firefox, Opera and Chrome support and it was "introduced by the World Wide
Web Consortium (W3C, the organisation that oversees the development of the
web¢s standards) in 2012".

Here's a quote from the first article:

https://www.theguardian.com/technolo...s-battery-life
"The researchers point out that the information a website receives is
surprisingly specific, containing the estimated time in seconds that the
battery will take to fully discharge, as well the remaining battery
capacity expressed as a percentage. "

"Worse still, on some platforms, the researchers found that it is possible
to determine the maximum battery capacity of the device with enough
queries, creating a semi-permanent metric to compare devices".