PHPXMLRPC Remote Code Execution

[GulfTech Security Research]

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# GulfTech Security Research June 29th, 2005
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# Vendor : Useful Information Inc.
# URL : http://phpxmlrpc.sourceforge.net/
# Version : PHPXMLRPC 1.1 && Earlier
# Risk : Remote Command Execution
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Description:
PHPXMLRPC aka XML-RPC For PHP is a PHP implementation of the XML-RPC
web RPC protocol, and was originally developed by Edd Dumbill of Useful
Information Company. As of the 1.0 stable release, the project has been
opened to wider involvement and moved to SourceForge. PHPXMLRPC is used
in a large number of popular web applications such as PostNuke, Drupal,
b2evolution, and TikiWiki. Unfortunately PHPXMLRPC is vulnerable to a
remote php code execution vulnerability that may be exploited by an
attacker to compromise a vulnerable system.



Remote Command Execution:
PHPXMLRPC is vulnerable to a very high risk remote php code execution
vulnerability that may allow for an attacker to compromise a vulnerable
webserver. The vulnerability is the result of unsanatized data being passed
directly into an eval() call in the parseRequest() function of the
XMLRPC server.


// decompose incoming XML into request structure
xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, true);
xml_set_element_handler($parser, "xmlrpc_se", "xmlrpc_ee");
xml_set_character_data_handler($parser, "xmlrpc_cd");
xml_set_default_handler($parser, "xmlrpc_dh");
if (!xml_parse($parser, $data, 1)) {
// return XML error as a faultCode
$r=new xmlrpcresp(0,
$xmlrpcerrxml+xml_get_error_code($parser),
sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($parser)),
xml_get_current_line_number($parser)));
xml_parser_free($parser);
} else {
xml_parser_free($parser);
$m=new xmlrpcmsg($_xh[$parser]['method']);
// now add parameters in
$plist="";
for($i=0; $i<sizeof($_xh[$parser]['params']); $i++) {
//print "<!-- " . $_xh[$parser]['params'][$i]. "-->\n";
$plist.="$i - " . $_xh[$parser]['params'][$i]. " \n";
eval('$m->addParam(' . $_xh[$parser]['params'][$i]. ");");
}

By creating an XML file that uses single quotes to escape into the eval()
call an attacker can easily execute php code on the target server. This
has a lot to do with the fact that magic_quotes_gpc() does not apply to
$HTTP_RAW_POST_DATA so using single quotes is not a problem.



Solution:
An updated version of PHPXMLRPC can be downloaded from their official
website,
and all users are advised to upgrade immediately.

http://sourceforge.net/project/showfiles.php?group_id=34455&package_id=26601

A special thanks to Ed Dumbill, Giunta Gaetano, and all of the other people
that helped get this fix out, and all of the people who helped us try and
track down developers who were using this third party XMLRPC library.



Related Info:
The original advisory can be found at the following location
http://www.gulftech.org/?node=research&article_id=00088-07022005


TikiWiki
http://tikiwiki.org/Download

PostNuke
http://news.postnuke.com/modules.php?op=modload&name=News&file=article&sid=2699

Drupal
http://drupal.org/drupal-4.6.2

b2evolution
http://b2evolution.net/downloads/index.html

b2
http://cafelog.com/

phpGroupWare
http://downloads.phpgroupware.org/

eGroupware
http://sourceforge.net/project/showfiles.php?group_id=78745

Serendipity Weblog
http://www.s9y.org/

phpAdsNew
http://phpadsnew.com/two/

Max Media Manager
http://max.awarez.net/




Credits:
James Bercegay of the GulfTech Security Research Team