JSでDoSる/ Shibuya.XSS techtalk #11

Shibuya.XSS techtalk #11 の発表資料です。

Transcript

1. for(;;){ alert(` `); } /* 2019/05/16 Shibuya.XSS techtalk #11*/ /* Masato Kinugawa */
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7. while(1){ alert(` `); }
8. • •
9. •
10. • • > decodeURIComponent("%E3%81%82"); < " " > decodeURIComponent("%FF"); ‣ Uncaught URIError: URI malformed
12. • • • > encodeURIComponent(" "); < "%E3%81%82" > encodeURIComponent("\uDC00"); ‣ Uncaught URIError: URI malformed
13. https://www.ecma-international.org/ecma-262/9.0/index.html#sec-encode
14. (function a(){ alert(` `); a(); })()
15. • • • • / \/ • " \" • \ \\ <script> userInput = "AAA\\\";alert(1)\/\/ <\/script>"; displayContents(); </script>
16. • <script> userInput = "AAA [ ] BBB"; displayContents(); </script>
17. • <script> userInput = "AAA BBB"; displayContents(); </script>
18. • https://www.ecma-international.org/ecma-262/9.0/index.html#table-33
19. • https://www.ecma-international.org/ecma-262/9.0/index.html#table-33
20. • <script> userInput = "AAA [U+2028] BBB"; displayContents(); </script>
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22. <script> userInput = "<!--<script>"; displayContents(); </script>
23. • • <script> userInput = "<!--<script>"; </script> <textarea></script> <img src=x onerror=alert(1)> </textarea>
24. • • https://html.spec.whatwg.org/multipage/scripting.html#restrictions-for-contents-of-script- elements
25. • <script> userInput = "<%"; </script> <textarea>%></script><img src=x onerror=alert(1)> </textarea> https://html5sec.org/#91 <xmp> <% </xmp> <textarea> %></xmp><img src=x onerror=alert(1)> </textarea>
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27. setInterval(` alert(\` \`) `,1);
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30. • • • userInfo = {"name": 123}// name = userInfo.name.toUpperCase() Uncaught TypeError: userInfo.name.toUpperCase is not a function
31. siteData = {"url":"https:// ...","title":{"toString":null},...}; url = "url: " + siteData.url; title = "title: " + siteData.title;
32. • • • ({toString: function(){alert(1)} })+""; ({valueOf : function(){alert(2)} })+"";
33. • • • > ({toString:null})+""; ‣ Uncaught TypeError: Cannot convert object to primitive value
34. • • • • •
35. • > typeof "aaa"; < ‣ "string" > typeof 123; < ‣ "number" > typeof true; < ‣ "boolean" > typeof []; < ‣ "object" > typeof {}; < ‣ "object" > typeof null; < ‣ "object"
36. • • > Array.isArray([]); < ‣ true > Array.isArray({}); < ‣ false > null === null < ‣ true
37. • • > Object.prototype.toString.call("aaa"); < ‣ "[object String]" > Object.prototype.toString.call(123); < ‣ "[object Number]" > Object.prototype.toString.call(true); < ‣ "[object Boolean]" > Object.prototype.toString.call([]); < ‣ "[object Array]" > Object.prototype.toString.call({}); < ‣ "[object Object]" > Object.prototype.toString.call(null); < ‣ "[object Null]"
38. <style>*{ color:expression( alert(" ") )}
39. • • • <toString>AAA</toString>
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41. • • function tellMeFruitColor(USER_INPUT){ fruits = { "apple":"red", "lemon":"yellow", "peach":"pink" }; if(fruits[USER_INPUT]){ return USER_INPUT + ": " + fruits[USER_INPUT]; }else{ return "I don't know that fruit"; } }
42. > tellMeFruitColor("apple"); < "apple: red" > tellMeFruitColor("lemon"); < "lemon: yellow" > tellMeFruitColor("strawberry"); < "I don't know that fruit" > tellMeFruitColor("toString"); < "toString: function toString() { [native code] }" > tellMeFruitColor("constructor"); < "constructor: function Object() { [native code] }" > tellMeFruitColor("__proto__"); < "__proto__: [object Object]"
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45. https://qiita.com/howdy39/items/35729490b024ca295d6c
46. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
47. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
48. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
49. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
50. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
51. if(fruits["toString"]){ return "toString" + ": " + fruits["toString"]; }else{ return "I don't know that fruit"; }
52. > ({"toString":function(){return "a"}})+""; < " " > ({"prop":"a"})+""; < "[object Object]"
53. whiteListTags = { "span":funcForSanitizingSpanElem, "div": funcForSanitizingDivElem, "a":" funcForSanitizingAElem, ... } // whiteListTags[ ] <toString> whiteListTags["toString"]()
54. fileIcons = { "txt":"https://example.com/img/icon-txt.gif", "png":"https://example.com/img/icon-png.gif", "jpg":" https://example.com/img/icon-jpg.gif ", ... } // fileIcons[ ] dos.constructor fileIcons["constructor"]
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56. • • function tellMeFruitColor(USER_INPUT){ fruits = { ... }; - if(fruits[USER_INPUT]){ + if(Object.prototype.hasOwnProperty.call(fruits,USER_INPUT)){ return USER_INPUT + ": " + fruits[USER_INPUT]; }else{ return "I don't know that fruit"; } }
57. > tellMeFruitColor("apple"); < "apple: red" > tellMeFruitColor("lemon"); < "lemon: yellow" > tellMeFruitColor("strawberry"); < "I don't know that fruit" > tellMeFruitColor("toString"); < "I don't know that fruit" > tellMeFruitColor("constructor"); < "I don't know that fruit" > tellMeFruitColor("__proto__"); < "I don't know that fruit"
58. • • fruits["toString"] undefined function tellMeFruitColor(USER_INPUT){ - fruits = { ... }; + fruits = Object.create(null); + fruits = Object.assign(fruits,{"apple":"red","lemon": ... }) if(fruits[USER_INPUT]){ return USER_INPUT + ": " + fruits[USER_INPUT]; }else{ return "I don't know that fruit"; } }
59. • • function tellMeFruitColor(USER_INPUT){ - fruits = { ... }; + fruits = new Map(["apple","red"], + ["lemon","yellow"], + ["peach","pink"]); - if(fruits[USER_INPUT]){ - return USER_INPUT + ": " + fruits[USER_INPUT]; + if(fruits.get(USER_INPUT)){ + return USER_INPUT + ": " + fruits.get(USER_INPUT); }else{ return "I don't know that fruit"; } }
60. ({toString: function(){ alert(` `); this+""; } })+"";
61. • •
62. • • • USER_INPUT = {"length": 1e10,"constructor":{"name":"Array"}}; if(USER_INPUT.constructor.name === "Array"){ array = []; for (var i = 0; i < USER_INPUT.length; i++) { array.push(USER_INPUT[i]); } }
63. ==== JS stack trace ========================================= Security context: 00000099763A5549 <JSObject> 1: /* anonymous */ [repl:~1] [pc=000000C1A3E8B9B9](this=00000382794865D9 <JSGlobal Object>) 5: /* anonymous */ [vm.js:65] [bytecode=000002EDD76E8421 offset=87](this=0000021A2A00C731 <ContextifyScript map = 00000203C25E1319>,options=0000021A2A00C709 <Object map = 00000203C25E13C9>) 6: defaultEval [repl.js:244] [bytecode=000002EDD76E7089 offset=445](this=0000021A2A00C7A1 <REPLServer ... FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory 1: node::DecodeWrite 2: node_module_register 3: v8::internal::FatalProcessOutOfMemory 4: v8::internal::FatalProcessOutOfMemory 5: v8::internal::Factory::NewUninitializedFixedArray 6: v8::internal::WasmDebugInfo::SetupForTesting 7: v8::internal::interpreter::BytecodeArrayRandomIterator::UpdateOffsetFromIndex 8: 000000C1A3D043C1
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67. for(;;){ alert(` `); } /* */