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Added content filtering of tags with javascript or data in values attr

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Case would be blocked by CSP but adding for cases where CSP may not be
active when content taken externally.

For #3636
This commit is contained in:
Dan Brown 2022-08-11 10:26:33 +01:00
parent 375abca1ee
commit 5f7cd735ea
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GPG Key ID: 46D9F943C24A2EF9
2 changed files with 14 additions and 4 deletions
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5
app/Util/HtmlContentFilter.php
View File

@ -45,6 +45,11 @@ class HtmlContentFilter
$badIframes = $xPath->query('//*[' . static::xpathContains('@src', 'data:') . '] | //*[' . static::xpathContains('@src', 'javascript:') . '] | //*[@srcdoc]'); $badIframes = $xPath->query('//*[' . static::xpathContains('@src', 'data:') . '] | //*[' . static::xpathContains('@src', 'javascript:') . '] | //*[@srcdoc]');
static::removeNodes($badIframes); static::removeNodes($badIframes);
// Remove tags hiding JavaScript or data uris in values attribute.
// For example, SVG animate tag can exploit javascript in values.
$badValuesTags = $xPath->query('//*[' . static::xpathContains('@values', 'data:') . '] | //*[' . static::xpathContains('@values', 'javascript:') . ']');
static::removeNodes($badValuesTags);
// Remove elements with a xlink:href attribute // Remove elements with a xlink:href attribute
// Used in SVG but deprecated anyway, so we'll be a bit more heavy-handed here. // Used in SVG but deprecated anyway, so we'll be a bit more heavy-handed here.
$xlinkHrefAttributes = $xPath->query('//@*[contains(name(), \'xlink:href\')]'); $xlinkHrefAttributes = $xPath->query('//@*[contains(name(), \'xlink:href\')]');

13
tests/Entity/PageContentTest.php
View File

@ -325,11 +325,14 @@ class PageContentTest extends TestCase
$pageView->assertDontSee('abc123abc123'); $pageView->assertDontSee('abc123abc123');
} }
public function test_svg_xlink_hrefs_are_removed() public function test_svg_script_usage_is_removed()
{ {
$checks = [ $checks = [
'<svg id="test" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100"><a xlink:href="javascript:alert(document.domain)"><rect x="0" y="0" width="100" height="100" /></a></svg>', '<svg id="test" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100"><a xlink:href="javascript:alert(document.domain)"><rect x="0" y="0" width="100" height="100" /></a></svg>',
'<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><use xlink:href="data:application/xml;base64 ,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHhtbG5zOnhsaW5rPSJodHRwOi8vd3d3LnczLm9yZy8xOTk5L3hsaW5rIj4KPGRlZnM+CjxjaXJjbGUgaWQ9InRlc3QiIHI9IjAiIGN4PSIwIiBjeT0iMCIgc3R5bGU9ImZpbGw6ICNGMDAiPgo8c2V0IGF0dHJpYnV0ZU5hbWU9ImZpbGwiIGF0dHJpYnV0ZVR5cGU9IkNTUyIgb25iZWdpbj0nYWxlcnQoZG9jdW1lbnQuZG9tYWluKScKb25lbmQ9J2FsZXJ0KCJvbmVuZCIpJyB0bz0iIzAwRiIgYmVnaW49IjBzIiBkdXI9Ijk5OXMiIC8+CjwvY2lyY2xlPgo8L2RlZnM+Cjx1c2UgeGxpbms6aHJlZj0iI3Rlc3QiLz4KPC9zdmc+#test"/></svg>', '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><use xlink:href="data:application/xml;base64 ,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHhtbG5zOnhsaW5rPSJodHRwOi8vd3d3LnczLm9yZy8xOTk5L3hsaW5rIj4KPGRlZnM+CjxjaXJjbGUgaWQ9InRlc3QiIHI9IjAiIGN4PSIwIiBjeT0iMCIgc3R5bGU9ImZpbGw6ICNGMDAiPgo8c2V0IGF0dHJpYnV0ZU5hbWU9ImZpbGwiIGF0dHJpYnV0ZVR5cGU9IkNTUyIgb25iZWdpbj0nYWxlcnQoZG9jdW1lbnQuZG9tYWluKScKb25lbmQ9J2FsZXJ0KCJvbmVuZCIpJyB0bz0iIzAwRiIgYmVnaW49IjBzIiBkdXI9Ijk5OXMiIC8+CjwvY2lyY2xlPgo8L2RlZnM+Cjx1c2UgeGxpbms6aHJlZj0iI3Rlc3QiLz4KPC9zdmc+#test"/></svg>',
'<svg><animate href=#xss attributeName=href values=javascript:alert(1) /></svg>',
'<svg><animate href="#xss" attributeName="href" values="a;javascript:alert(1)" /></svg>',
'<svg><animate href="#xss" attributeName="href" values="a;data:alert(1)" /></svg>',
]; ];
$this->asEditor(); $this->asEditor();
@ -341,9 +344,11 @@ class PageContentTest extends TestCase
$pageView = $this->get($page->getUrl()); $pageView = $this->get($page->getUrl());
$pageView->assertStatus(200); $pageView->assertStatus(200);
$this->withHtml($pageView)->assertElementNotContains('.page-content', 'alert'); $html = $this->withHtml($pageView);
$this->withHtml($pageView)->assertElementNotContains('.page-content', 'xlink:href'); $html->assertElementNotContains('.page-content', 'alert');
$this->withHtml($pageView)->assertElementNotContains('.page-content', 'application/xml'); $html->assertElementNotContains('.page-content', 'xlink:href');
$html->assertElementNotContains('.page-content', 'application/xml');
$html->assertElementNotContains('.page-content', 'javascript');
} }
} }