SEC Consult Vulnerability Lab Security Advisory < 20120626-0 > ======================================================================= title: Local file disclosure via XXE injection product: Zend Framework vulnerable version: 1.11.11 1.12.0 RC1 2.0.0 beta4 and earlier versions / branches fixed version: 1.11.12 1.12.0 RC2 2.0.0 beta5 / trunk impact: Critical homepage: http://framework.zend.com/ found: 2012-06-18 by: K. Gudinavicius SEC Consult Vulnerability Lab https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "Extending the art & spirit of PHP, Zend Framework is based on simplicity, object-oriented best practices, corporate friendly licensing, and a rigorously tested agile codebase. Zend Framework is focused on building more secure, reliable, and modern Web 2.0 applications & web services, and consuming widely available APIs from leading vendors like Google, Amazon, Yahoo!, Flickr, as well as API providers and cataloguers like StrikeIron and ProgrammableWeb." Source: http://framework.zend.com/about/overview Vulnerability overview/description: ----------------------------------- The XmlRpc package of Zend Framework is vulnerable to XML eXternal Entity Injection attacks (both server and client). The SimpleXMLElement class (SimpleXML PHP extension) is used in an insecure way to parse XML data. External entities can be specified by adding a specific DOCTYPE element to XML-RPC requests. By exploiting this vulnerability an application may be coerced to open arbitrary files and/or TCP connections. Other software that uses the XmlRpc package of Zend Framework is then also vulnerable to XML eXternal Entity Injection attacks! Proof of concept: ----------------- For example, the loadXml function (Zend\XmlRpc\Request.php and Response.php) fails to disable external entities when parsing XML data. There is no call to the libxml_disable_entity_loader function before initializing the SimpleXMLElement class. Related code excerpt: public function loadXml($request) { if (!is_string($request)) { $this->_fault = new Zend_XmlRpc_Fault(635); $this->_fault->setEncoding($this->getEncoding()); return false; } try { $xml = new SimpleXMLElement($request); } catch (Exception $e) { // Not valid XML $this->_fault = new Zend_XmlRpc_Fault(631); $this->_fault->setEncoding($this->getEncoding()); return false; } [...] } If a web application uses the Zend_XmlRpc_Server() class (Zend\XmlRpc\Server.php) to handle XML-RPC requests, it is possible to disclose arbitrary local files from the remote system. The following HTTP POST request to the vulnerable XmlRpc server application illustrates the exploitation of this vulnerability. POST /xmlrpc_server.php HTTP/1.1 Host: $host <?xml version="1.0"?> <!DOCTYPE foo [ <!ELEMENT methodName ANY > <!ENTITY xxe SYSTEM "file:///etc/passwd" >]> <methodCall> <methodName>&xxe;</methodName> </methodCall> Vulnerable / tested versions: ----------------------------- The vulnerability has been verified to exist in versions 1.11.11 and 2.0.0beta4 of Zend Framework, which were the most recent versions at the time of discovery. Furthermore, previous versions and 1.12.0 RC1 are also affected. Older branches are also affected but won't be fixed by Zend as they are not maintained anymore. Their policy is to fix the current minor release and the immediate previous minor release. Vendor contact timeline: ------------------------ 2012-06-18: Contacting vendor through zf-security@zend.com 2012-06-18: Vendor: Very fast reply, fixes issue already after 3 hours! 2012-06-18: Confirming server-side fix, adding recommendation for XmlRpc client code 2012-06-19: Vendor: XmlRpc client code also fixed Confirming fix 2012-06-20: Contacting local CERT 2012-06-20: Vendor: starts packaging, expected release of 1.11.12 and 1.12.0RC2 by end of week, ZF2 trunk already fixed, next beta 2.0.0beta5 will be released late next week 2012-06-22: Vendor: Packages are created and staged, packages and security announcement will be released on Monday 2012-06-25: New packages and Zend security advisory released by vendor 2012-06-26: SEC Consult releases security advisory Solution: --------- Upgrade to the latest version available, e.g. * v1.11.12 * v1.12.0 RC2 * update ZF2 master trunk If you are using an older branch you are urged to upgrade! Zend framework security advisory: http://framework.zend.com/security/advisory/ZF2012-01 Download link for new releases: http://framework.zend.com/download/latest Commits: -------- http://framework.zend.com/code/log.php?repname=Zend+Framework&path=%2F * Zend Framework 1.X Trunk: http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2Ftrunk&rev=24970&peg=24970 http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2F&rev=24975 * 1.11.X: http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2Fbranches%2F&rev=24971&peg=24971 http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2Fbranches%2F&rev=24972&peg=24972 http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2F&rev=24976 * 1.12.0: http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2Fbranches%2F&rev=24973&peg=24973 http://framework.zend.com/code/revision.php?repname=Zend+Framework&path=%2F&rev=24977 * Zend Framework 2.0 https://github.com/zendframework/zf2/pull/1523 Workaround: ----------- None Advisory URL: ------------- https://www.sec-consult.com/en/advisories.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Unternehmensberatung GmbH Office Vienna Mooslackengasse 17 A-1190 Vienna Austria Tel.: +43 / 1 / 890 30 43 - 0 Fax.: +43 / 1 / 890 30 43 - 25 Mail: research at sec-consult dot com https://www.sec-consult.com EOF K. Gudinavicius, J. Greil / @2012