Name: BAD Content Length
Version: 1.1
Description: Denies any POST request that doesnt have a Content-Length Header..
Rules: 
RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{REQUEST_URI} !^%relative_root%(wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{HTTP:Content-Length} ^$
RewriteRule .* - [F,NS,L]