PT-2013-15: XML External Entities Injection in vBulletin 5 Connect

Vulnerable software

Version: 5 Beta 27 and earlier


Severity level

Severity level: Medium
Impact: Internal Network Resources and File System Access, Denial of Service 
Access Vector: Remote

CVSS v2:
Base Score: 6.4
Vector: (AV:N/AC:L/Au:N/C:P/I:N/A:P)

CVE: not assigned

Software description

vBulletin 5 Connect provides unparalleled capabilities for building community websites. The software facilitates increased content creation, more engaging content discovery and simplified site management.

Vulnerability description

The specialists of the Positive Research center have detected an XML External Entities Injection vulnerability in vBulletin 5 Connect.

The vulnerability was detected in "appender_socket_server.php" of the Apache log4php library used by vBulletin. PHP's built-in SoapClient class allows the use of external entities while parsing SOAP wsdl files which enables an attacker to read arbitrary files. The vulnerable script starts a local proxy on port 4242 and unserializes incoming data executing "getLoggerName" method on unserialized object. An attacker can send serialized SoapClient object initialized in non-wsdl mode which will make PHP to parse remote XML-document automatically and thus enables him to read arbitrary files via XXE including vBulletin configuration file.

How to fix

Update your software up to the latest version

Advisory status

07.02.2013 - Vendor gets vulnerability details
11.02.2013 - Vendor releases fixed version and details
23.10.2013 - Public disclosure


The vulnerability was detected by Arseny Reutov, Positive Research Center (Positive Technologies Company)


Reports on the vulnerabilities previously discovered by Positive Research: