Name: BAD Content Type
Version: 1.1
Description: Denies any POST request with a content type other than application/x-www-form-urlencoded|multipart/form-data..
Rules: 
RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{REQUEST_URI} !^%relative_root%(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{HTTP:Content-Type} !^(application/x-www-form-urlencoded|multipart/form-data.*(boundary.*)?)$ [NC]
RewriteRule .* - [F,NS,L]