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Simple Ads Manager WordPress plugin unauthenticated PHP Object injection
vulnerability
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Yorick Koster, July 2016

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Abstract
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A PHP Object injection vulnerability was found in the Simple Ads Manager
WordPress plugin. The unauthenticated PHP Object injection vulnerability
can be used by an unautenthicated user to instantiate arbitrary PHP
Objects. This issue can potentially result in arbitrary code execution,
but this has not been confirmed.

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OVE ID
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OVE-20160712-0041

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Tested versions
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This issue was succesfully tested on the Simple Ads Manager [2]
WordPress plugin version 2.9.8.125.

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Fix
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There is currently no fix available.

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Introduction
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The Simple Ads Manager [2] WordPress Plugin is an easy to use plugin
providing a flexible logic of displaying advertisements. A PHP Object
injection [3] vulnerability was found in Simple Ads Manager WordPress
plugin. The unauthenticated PHP Object injection vulnerability can be
used by an unautenthicated  user to instantiate arbitrary PHP Objects.

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Details
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This issue is possible due to two unsafe calls to unserialize() in the
sam-ajax-loader.php file. The input is taken directly from the POST
request as can be seen in the following code fragment:

sam-ajax-loader.php:

if ( in_array( $action, $allowed_actions ) ) {
	switch ( $action ) {
		case 'sam_ajax_load_place':
			echo json_encode( array( 'success' => false, 'error' =>
'Deprecated...' ) );
			break;
	
		case 'sam_ajax_load_ads':
			if ( ( isset( $_POST['ads'] ) && is_array( $_POST['ads'] ) ) &&
isset( $_POST['wc'] ) ) {
				$clauses = unserialize( base64_decode( $_POST['wc'] ) );

This issue can potentially result in arbitrary code execution, but this
has not been confirmed.

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References
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[1] https://sumofpwn.nl/advisory/2016/simple_ads_manager_wordpress_plugin_unauthenticated_php_object_injection_vulnerability.html
[2] https://wordpress.org/plugins/simple-ads-manager/
[3] https://www.owasp.org/index.php/PHP_Object_Injection