Upgrade to Pro — share decks privately, control downloads, hide ads and more …

How CSP Will (maybe) Solve the XSS Problem

Avatar for Neil Matatall Neil Matatall
September 12, 2014
Programming
0
160

How CSP Will (maybe) Solve the XSS Problem

More ramblings about how awesome csp and how it solves all of your problems.

Avatar for Neil Matatall

Neil Matatall

September 12, 2014
Tweet

More Decks by Neil Matatall

See All by Neil Matatall
Twubhubbook - It's like appsec, but for startups (with notes)
Avatar for Neil Matatall oreoshake
0
140
Twubhubbook - it's like appsec, but for startups (without notes)
Avatar for Neil Matatall oreoshake
0
130
Automatic Application Security v2
Avatar for Neil Matatall oreoshake
0
150
JRubyFX For Web Developers
Avatar for Neil Matatall oreoshake
0
250
Automatic Application Security
Avatar for Neil Matatall oreoshake
0
160
Putting your robots to work: Security Automation @Twitter
Avatar for Neil Matatall oreoshake
2
180
BSidesLA Managing Content Security Policy
Avatar for Neil Matatall oreoshake
3
1.1k

Other Decks in Programming

See All in Programming
Unicodeどうしてる？ PHPから見たUnicode対応と他言語での対応についてのお伺い
Avatar for てきめん tekimen youkidearitai
PRO
0
860
Python札幌 LT資料
Avatar for t3tra t3tra
7
1.1k
AIで開発はどれくらい加速したのか？AIエージェントによるコード生成を、現場の評価と研究開発の評価の両面からdeep diveしてみる
Avatar for どすこい daisuketakeda
1
830
なぜSQLはAIぽく見えるのか/why does SQL look AI like
Avatar for florets1 florets1
0
330
そのAIレビュー、レビューしてますか？ / Are you reviewing those AI reviews?
Avatar for r-kagaya rkaga
3
3.4k
Denoのセキュリティに関する仕組みの紹介 (toranoana.deno #23)
Avatar for uki00a uki00a
0
250
AIエージェント、”どう作るか”で差は出るか？ / AI Agents: Does the "How" Make a Difference?
Avatar for r-kagaya rkaga
4
1.9k
AIによるイベントストーミング図からのコード生成 / AI-powered code generation from Event Storming diagrams
Avatar for nrs nrslib
2
1.6k
Vibe codingでおすすめの言語と開発手法
Avatar for uyuki uyuki234
0
180
Claude Codeの「Compacting Conversation」を体感50%減！ CLAUDE.md + 8 Skills で挑むコンテキスト管理術
Avatar for Kazuki Murahama kmurahama
1
780
Findy AI+の開発、運用におけるMCP活用事例
Avatar for starfish719 starfish719
0
2.2k
責任感のあるCloudWatchアラームを設計しよう
Avatar for アキキー akihisaikeda
3
110

Featured

See All Featured
Git: the NoSQL Database
Avatar for Brandon Keepers bkeepers
PRO
432
66k
RailsConf 2023
Avatar for Aaron Patterson tenderlove
30
1.3k
ピンチをチャンスに：未来をつくるプロダクトロードマップ #pmconf2020
Avatar for Aki / @LoveIdahoBurger aki_iinuma
128
55k
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
Avatar for mongodb mongodb
49
9.8k
Dealing with People You Can't Stand - Big Design 2015
Avatar for Cassini Nazir cassininazir
367
27k
Information Architects: The Missing Link in Design Systems
Avatar for Michelle Chin soysaucechin
0
750
Testing 201, or: Great Expectations
Avatar for Joseph Mastey jmmastey
46
7.9k
Building an army of robots
Avatar for Kyle Neath kneath
306
46k
So, you think you're a good person
Avatar for Per Axbom axbom
PRO
2
1.9k
The Spectacular Lies of Maps
Avatar for Per Axbom axbom
PRO
1
440
職位にかかわらず全員がリーダーシップを発揮するチーム作り / Building a team where everyone can demonstrate leadership regardless of position
Avatar for MADOX madoxten
54
49k
Gemini Prompt Engineering: Practical Techniques for Tangible AI Outcomes
Avatar for Mfonobong Umondia mfonobong
2
260

Transcript

  1. How CSP Will (maybe) Solve the XSS Problem Neil Matatall

    OWASP SD 4/17/2014

  2. Me • Twitter appsec engineer • I’m actually just a

    developer • In the business of going out of business • Sick and tired of fixing XSS

  3. XSS is so 1998

  4. So is XSS prevention

  5. What is XSS <input name=“id” value=“<%=id%>”>

  6. What is XSS ”><script>badStuff()</script>

  7. What is XSS <input name=“id” value=“”> <script>badStuff()</script> ”>

  8. What is XSS <script> var id=<%=id%>; </script>

  9. What is XSS 0;badStuff();

  10. What is XSS <script> var id=0; badStuff() </script>

  11. What is XSS <script> setInterval(1000, ‘<%=todo%>’) </script>

  12. What is XSS badStuff();

  13. What is XSS <script> setInterval(1000, ‘badStuff()’) </script>

  14. What is XSS <input name=“id” onBlur=“doStuff(<%=id %>)”>

  15. What is XSS ); badStuff(

  16. What is XSS <input name=“id” onBlur=“doStuff(); badStuff()”>

  17. What is XSS <a href=“<%=link%>”>Hi Mom!</a>

  18. What is XSS javascript:badThings()

  19. What is XSS <a href=“javascript:badThings()”> Hi Mom!</a>

  20. What is XSS <a href=“#” onClick=“doThing(‘<%=link%>’)”> Hi Mom! </a>

  21. What is XSS &#39;);badStuff(&#39;

  22. What is XSS <a href=“#” onClick= “doThing(‘&#39;);badStuff(&#39;’)” > Hi Mom!

    </a>

  23. What is XSS <a href=“#” onClick= “doThing(‘’);badStuff(‘’)”> Hi Mom! </a>

  24. What is DOM XSS <script> document.body.innerHTML = document.getElementById(‘name’).value; </script>

  25. What is DOM XSS

  26. What is DOM XSS <body> <img src=x onError=badThings()> </body>

  27. What is DOM XSS <script> var name = $(‘#name’).val $(‘body’).html(name)

    </script>

  28. What is DOM XSS

  29. What is DOM XSS <body> <img src=x onError=badThings()> </body>

  30. jQuery is XSS $(data)

  31. What is XSS <style> a { color: <%=usersFavoriteColor%>; } </style>

  32. What is XSS I dunno, something with SVG, CSS Expressions,

    etc. The list grows.

  33. Because Dr. Mario

  34. Because Dr. Mario

  35. Why do those crazy things?

  36. CODE != DATA “select * from table where id =

    “ + id “<a href=“ + link + “>text</a>”

  37. But we don’t do stupid things

  38. I will religiously escape content

  39. I will religiously escape content part 2

  40. JSFuck - Write any JavaScript with 6 Characters: []()!+ I

    will religiously escape content part 3
  41. None

  42. I’ll sanitize / validate input

  43. I’ll use a scanner

  44. I’ll perform periodic assessments

  45. Security is about layers

  46. None

  47. Thermos? Koozie?

  48. <script>goodStuff()</script> <script>badStuff()</script> How does the browser know?

  49. What is dangerous? • inline javascript • <script>…</script> • <input

    onBlur=“…”> • <a href=“javascript:…”> • on-the-fly code generation • setTimeout, eval, new Function(“…”)

  50. What’s a CSP??? default-src ‘self’; connect-src ‘self’; font-src ‘self’ data:;

    frame-src ‘self’ about: javascript:; frame-ancestors https://twitter.com; img-src https://mycdn.xom data:; media-src ‘https://mycdn.xom; object-src ‘none’; script-src https://mycdn.xom; style-src 'unsafe-inline' https://mycdn.xom; report-uri https://twitter.com/scribes/csp_report

  51. CSP is more than XSS protection

  52. Nothing is free

  53. Report-Only mode

  54. Techniques for removing inline javascript

  55. Removing the dangerous stuff

  56. CSP 1.1 • Whitelisting inline <script> in a safe way

  57. Inline code <script> stuff() </script>

  58. Nonces <script nonce=“34298734…”> stuff() </script>

  59. Hashes <script> stuff() </script>

  60. Hashes are more secure, and more limited than nonces

  61. What you still can’t do • Inline event handlers •

    <input onBlur=“doGoodThing()”> • <a href=“javascript:…”> • Dynamic javascript • <script> var id=<%=id%> </script> • Hash values won’t match • Nonce provides absolutely no security

  62. Automatic CSP Protection (Silverish bullet)

  63. Whitelisting javascript • Find all javascript • Compute all hash

    values • Whitelist scripts with corresponding hashes

  64. Assume: Sane web framework • Do a regular expression search

    over all templates, capture all inline javascript • Store a map of the hash(es) in each individual file • Each time the file is rendered, add the corresponding hashes to the header

  65. Developer productivity • Serve dynamic hash values in (!production), serve

    hardcoded hash values in production
  66. None