------------------------------------------------------------------------ Cross-Site Scripting in WangGuard WordPress Plugin ------------------------------------------------------------------------ Yorick Koster, July 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ A Cross-Site Scripting vulnerability was found in the WangGuard WordPress Plugin. This issue allows an attacker to perform a wide variety of actions, such as stealing Administrators' session tokens, or performing arbitrary actions on their behalf. In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website. ------------------------------------------------------------------------ OVE ID ------------------------------------------------------------------------ OVE-20160724-0030 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on WangGuard [2] WordPress Plugin version 1.7.1. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ This issue is resolved in WangGuard version 1.7.2 [3]. ------------------------------------------------------------------------ Introduction ------------------------------------------------------------------------ The WangGuard [2] WordPress Plugin protects against sploggers and spam users registration. A Cross-Site Scripting vulnerability was found in the WangGuard WordPress Plugin. This issue allows an attacker to perform a wide variety of actions, such as stealing Administrators' session tokens, or performing arbitrary actions on their behalf. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ The issue exists in the file wangguard-admin.php and is caused by the lack of output encoding on the security questions & answers. It should be noted that this functionality is also vulnerable to Cross-Site Request Forgery. jQuery("#wangguardnewquestionbutton").click(function() { jQuery("#wangguardnewquestionerror").hide(); var wgq = jQuery("#wangguardnewquestion").val(); var wga = jQuery("#wangguardnewquestionanswer").val(); if ((wgq=='') || (wga=='')) { jQuery("#wangguardnewquestionerror").slideDown(); return; } data = { action : 'wangguard_ajax_questionadd', q : wgq, a : wga }; jQuery.post(ajaxurl, data, function(response) { if (response!='0') { jQuery("#wangguard-question-noquestion").remove(); var newquest = '

'; newquest += ': '+wgq+'
'; newquest += ': '+wga+'
'; newquest += '

'; jQuery("#wangguard-new-question-container").append(newquest); jQuery("#wangguardnewquestion").val(""); jQuery("#wangguardnewquestionanswer").val(""); } else if (response=='0') { jQuery("#wangguardnewquestionerror").slideDown(); } }); }); In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website. ------------------------------------------------------------------------ Proof of concept ------------------------------------------------------------------------ [h3]References[/h3] [1] https://sumofpwn.nl/advisory/2016/cross_site_scripting_in_wangguard_wordpress_plugin.html [2] https://wordpress.org/plugins/wangguard/ [3] https://downloads.wordpress.org/plugin/wangguard.1.7.2.zip