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IgorMinarpetebacondarwin
IgorMinar
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petebacondarwin
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fix($sanitize): add mXSS protection
Closes angular#12524
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3 files changed

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‎docs/content/error/$sanitize/uinput.ngdoc‎

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@@ -0,0 +1,13 @@
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@ngdoc error
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@name $sanitize:uinput
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@fullName Failed to sanitize html because the input is unstable
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@description
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This error occurs when `$sanitize` sanitizer tries to check the input for possible mXSS payload and the verification
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errors due to the input mutating indefinitely. This could be a sign that the payload contains code exploiting an mXSS
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vulnerability in the browser.
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mXSS attack exploit browser bugs that cause some browsers parse a certain html strings into DOM, which once serialized
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doesn't match the original input. These browser bugs can be exploited by attackers to create payload which looks
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harmless to sanitizers, but due to mutations caused by the browser are turned into dangerous code once processed after
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sanitization.

‎src/ngSanitize/sanitize.js‎

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@@ -334,6 +334,23 @@ function htmlParser(html, handler) {
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html = '' + html;
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}
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inertBodyElement.innerHTML = html;
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//mXSS protection
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var mXSSAttempts = 5;
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do {
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if (mXSSAttempts === 0) {
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throw $sanitizeMinErr('uinput', "Failed to sanitize html because the input is unstable");
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}
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mXSSAttempts--;
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// strip custom-namespaced attributes on IE<=11
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if (document.documentMode <= 11) {
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stripCustomNsAttrs(inertBodyElement);
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}
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html = inertBodyElement.innerHTML; //trigger mXSS
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inertBodyElement.innerHTML = html;
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} while (html !== inertBodyElement.innerHTML);
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var node = inertBodyElement.firstChild;
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while (node) {
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switch (node.nodeType) {
@@ -459,5 +476,39 @@ function htmlSanitizeWriter(buf, uriValidator) {
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}
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/**
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* When IE9-11 comes across an unknown namespaced attribute e.g. 'xlink:foo' it adds 'xmlns:ns1' attribute to declare
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* ns1 namespace and prefixes the attribute with 'ns1' (e.g. 'ns1:xlink:foo'). This is undesirable since we don't want
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* to allow any of these custom attributes. This method strips them all.
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*
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* @param node Root element to process
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*/
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function stripCustomNsAttrs(node) {
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if (node.nodeType === Node.ELEMENT_NODE) {
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var attrs = node.attributes;
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for (var i = 0, l = attrs.length; i < l; i++) {
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var attrNode = attrs[i];
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var attrName = attrNode.name.toLowerCase();
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if (attrName === 'xmlns:ns1' || attrName.indexOf('ns1:') === 0) {
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node.removeAttributeNode(attrNode);
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i--;
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l--;
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}
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}
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}
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var nextNode = node.firstChild;
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if (nextNode) {
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stripCustomNsAttrs(nextNode);
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}
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nextNode = node.nextSibling;
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if (nextNode) {
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stripCustomNsAttrs(nextNode);
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}
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}
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// define ngSanitize module and register $sanitize service
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angular.module('ngSanitize', []).provider('$sanitize', $SanitizeProvider);

‎test/ngSanitize/sanitizeSpec.js‎

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@@ -216,11 +216,18 @@ describe('HTML', function() {
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expectHTML(false).toBe('false');
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});
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it('should strip svg elements if not enabled via provider', function() {
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expectHTML('<svg width="400px" height="150px" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red"></svg>')
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.toEqual('');
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});
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if (/Chrome/.test(window.navigator.userAgent)) {
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it('should prevent mXSS attacks', function() {
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expectHTML('<a href="&#x3000;javascript:alert(1)">CLICKME</a>').toBe('<a>CLICKME</a>');
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});
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}
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describe('SVG support', function() {
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@@ -238,38 +245,47 @@ describe('HTML', function() {
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it('should not ignore white-listed svg camelCased attributes', function() {
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expectHTML('<svg preserveAspectRatio="true"></svg>')
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.toEqual('<svg preserveAspectRatio="true"></svg>');
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.toBeOneOf('<svg preserveAspectRatio="true"></svg>',
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'<svg preserveAspectRatio="true" xmlns="http://www.w3.org/2000/svg"></svg>');
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});
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it('should sanitize SVG xlink:href attribute values', function() {
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expectHTML('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a xlink:href="javascript:alert()"></a></svg>')
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.toBeOneOf('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a></a></svg>',
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>');
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a xmlns:xlink="http://www.w3.org/1999/xlink"></a></svg>');
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expectHTML('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a xlink:href="https://example.com"></a></svg>')
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.toBeOneOf('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a xlink:href="https://example.com"></a></svg>',
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a xlink:href="https://example.com"></a></svg>');
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a xlink:href="https://example.com"></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a xlink:href="https://example.com" xmlns:xlink="http://www.w3.org/1999/xlink"></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://example.com"></a></svg>');
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});
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it('should sanitize unknown namespaced SVG attributes', function() {
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expectHTML('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a xlink:foo="javascript:alert()"></a></svg>')
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.toBeOneOf('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a></a></svg>',
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>');
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a></a></svg>');
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expectHTML('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a xlink:bar="https://example.com"></a></svg>')
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.toBeOneOf('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><a></a></svg>',
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>');
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'<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><a></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a></a></svg>');
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});
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it('should not accept SVG animation tags', function() {
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expectHTML('<svg xmlns:xlink="http://www.w3.org/1999/xlink"><a><text y="1em">Click me</text><animate attributeName="xlink:href" values="javascript:alert(1)"/></a></svg>')
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.toEqual('<svg xmlns:xlink="http://www.w3.org/1999/xlink"><a><text y="1em">Click me</text></a></svg>');
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.toBeOneOf('<svg xmlns:xlink="http://www.w3.org/1999/xlink"><a><text y="1em">Click me</text></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a><text y="1em">Click me</text></a></svg>');
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expectHTML('<svg><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?"><circle r="400"></circle>' +
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'<animate attributeName="xlink:href" begin="0" from="javascript:alert(1)" to="&" /></a></svg>')
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.toBeOneOf('<svg><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?"><circle r="400"></circle></a></svg>',
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'<svg><a xlink:href="?" xmlns:xlink="http://www.w3.org/1999/xlink"><circle r="400"></circle></a></svg>');
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'<svg><a xlink:href="?" xmlns:xlink="http://www.w3.org/1999/xlink"><circle r="400"></circle></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a xlink:href="?" xmlns:xlink="http://www.w3.org/1999/xlink"><circle r="400"></circle></a></svg>',
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'<svg xmlns="http://www.w3.org/2000/svg"><a xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="?"><circle r="400"></circle></a></svg>');
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});
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});
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