[mod-security-users] How to block request that don't have a specific cookie

[FrzzMan <fr...@gm...>]

Hello,

My site have been DDoSed for a month now :(

I tried to set up a filter that block every request that don't have a
specific cookie, but I can't find noway to 
set it up, it can check a existed cookie to match the value,
but if that cookie is not existed, it allow the 
request.

Please help... thank you in advance.