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Mitigating Maliciousness -- jQuery Europe 2013

Mike West
February 23, 2013

Mitigating Maliciousness -- jQuery Europe 2013

jQuery has made it possible for developers to move more and more complex application logic down from the server to the client. This is a huge opportunity for JavaScript developers, and at the same time presents a tempting target for folks with malicious intent. It's more critical than ever to ensure that we're doing the right things with regard to security, and happily, modern browsers are here to help. Here, we'll talk about some of the new ways in which you can mitigate the effects of cross-site scripting and other attacks.

Mike West

February 23, 2013
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  1. <style> p { color: {{USER_COLOR}}; } </style> <p> Hello {{USER_NAME}},

    view your <a href="{{USER_URL}}">Account</a>. </p> <script> var id = {{USER_ID}}; </script> <!-- DEBUG: {{INFO}} -->
  2. [][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[]) [+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]][([][(![]+[])[+[[+[]]]]+([][[]]+[]) [+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[] +!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]]]]+([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[] +!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]] +(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]]]+([][[]]+[])[+[[+!+[]]]]+(![]+[])[+ [[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[+!+[]]]]+([][[]]+[])[+[[+[]]]]+([][(![]+[])[+ [[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+ (!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+ ([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+

    [])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[] +!+[]]]]+(!![]+[])[+[[+!+[]]]]]((![]+[])[+[[+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[!+[]+!+ []+!+[]]]]+(!![]+[])[+[[+!+[]]]]+(!![]+[])[+[[+[]]]]+([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+ []+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+ (!![]+[])[+[[+!+[]]]]]+[])[+[[+!+[]]]+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+[+!+[]]+([][(![]+[])[+[[+[]]]]+ ([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+ [[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[+!+[]]]+[[!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]]])()
  3. [][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[]) [+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]][([][(![]+[])[+[[+[]]]]+([][[]]+[]) [+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[] +!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]]]]+([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[] +!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]] +(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]]]+([][[]]+[])[+[[+!+[]]]]+(![]+[])[+ [[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[+!+[]]]]+([][[]]+[])[+[[+[]]]]+([][(![]+[])[+ [[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+ (!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+ ([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+

    [])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[] +!+[]]]]+(!![]+[])[+[[+!+[]]]]]((![]+[])[+[[+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[!+[]+!+ []+!+[]]]]+(!![]+[])[+[[+!+[]]]]+(!![]+[])[+[[+[]]]]+([][(![]+[])[+[[+[]]]]+([][[]]+[])[+[[!+[]+!+ []+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+[[!+[]+!+[]+!+[]]]]+ (!![]+[])[+[[+!+[]]]]]+[])[+[[+!+[]]]+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+[+!+[]]+([][(![]+[])[+[[+[]]]]+ ([][[]]+[])[+[[!+[]+!+[]+!+[]+!+[]+!+[]]]]+(![]+[])[+[[!+[]+!+[]]]]+(!![]+[])[+[[+[]]]]+(!![]+[])[+ [[!+[]+!+[]+!+[]]]]+(!![]+[])[+[[+!+[]]]]]+[])[+[[+!+[]]]+[[!+[]+!+[]+!+[]+!+[]+!+[]+!+[]]]])() alert(1)
  4. $ curl -I http://mkw.st/ HTTP/1.1 301 Moved Permanently Server: nginx/1.3.7

    Date: Sun, 11 Nov 2012 19:36:15 GMT Content-Type: text/html Content-Length: 184 Connection: keep-alive Keep-Alive: timeout=20 Location: https://mkw.st/
  5. Limit the browser’s capabilities “Every program and every privileged user

    of the system should operate using the least amount of privilege necessary to complete the job.” Jerome H. Saltzer, "Protection and the control of information sharing in multics"
  6. Content-Security-Policy: default-src 'none'; style-src https://mikewestdotorg.hasacdn.net; frame-src https://www.youtube.com http://www.slideshare.net; script-src https://mikewestdotorg.hasacdn.net

    https://ssl.google-analytics.com; img-src 'self' https://mikewestdotorg.hasacdn.net https://ssl.google-analytics.com data:; font-src https://mikewestdotorg.hasacdn.net
  7. Content-Security-Policy: default-src ...; script-src ...; object-src ...; style-src ...; img-src

    ...; media-src ...; frame-src ...; font-src ...; connect-src ...; sandbox ...; report-uri https://example.com/reporter.cgi
  8. <!-- index.html --> <script src="clickHandler.js"></script> <button class="clickable">Click me!</button> <a href="#"

    class="clickable">Click me!</a> <!-- clickHandler.js --> function handleClick() { ... } document.addEventListener('DOMContentLoader', function() { for (var e in document.querySelectorAll('.clickable')) e.addEventListener('click', clickHandler); });
  9. Content-Security-Policy-Report-Only: default-src https:; report-uri https://example.com/csp-violations { "csp-report": { "document-uri": "http://example.org/page.html",

    "referrer": "http://evil.example.com/haxor.html", "blocked-uri": "http://evil.example.com/image.png", "violated-directive": "default-src 'self'", "original-policy": "...", "line-number": "10" } }
  10. <iframe src="page.html" sandbox></iframe> <!-- * Unique origin * No plugins.

    * No script. * No form submissions. * No top-level navigation. * No popups. * No autoplay. * No pointer lock. * No seamless iframes. -->
  11. <!-- User-generated content? (in The Near Future™) --> <iframe seamless

    srcdoc="<p>This is a comment!</p>" sandbox></iframe>