Remco Vermeulen, July 2016

Google Analytics Counter Tracker WordPress Plugin unauthenticed PHP Object injection vulnerability

Abstract

A PHP Object injection vulnerability was found in Google Analytics Counter Tracker, which can be used by an unautenthicated user to instantiated arbitrary PHP Objects. Using this vulnerability it is possible to execute arbitrary PHP code.

Contact

For feedback or questions about this advisory mail us at sumofpwn at securify.nl

The Summer of Pwnage

This issue has been found during the Summer of Pwnage hacker event, running from July 1-29. A community summer event in which a large group of security bughunters (worldwide) collaborate in a month of security research on Open Source Software (WordPress this time). For fun. The event is hosted by Securify in Amsterdam.

OVE ID

OVE-20160712-0035

Tested versions

This issue was succesfully tested on the Google Analytics Counter Tracker WordPress Plugin version 3.1.5.

Fix

This issue has been addressed in Google Analytics Counter Tracker version 3.5.1.

Introduction

Google Analytics Counter Tracker analyse the visitors hits on you website and display it graphically. A PHP Object injection vulnerability was found in Google Analytics Counter Tracker, which can be used by an unautenthicated user to instantiated arbitrary PHP Objects.

Details

This issue is possible due to an unsafe call to unserialize() in the proccessRequest() method. The input is taken directly from the wpadm_ga_request cookie as can be seen in the following code fragment:

class.wpadm-ga.php:

protected static function proccessRequest() {
   $request_name = self::REQUEST_PARAM_NAME;
   $params = unserialize(base64_decode($_POST[$request_name]));
   
   $v = self::verifySignature($params['sign'], get_option('wpadm_ga_pub_key'), md5(serialize($params['data'])));

It has been confirmed that this issues can be used to execute arbitrary PHP code.