Irule for Data group List to Block specific cookie

I am far from a programmer and irule expert but these are basically what you need to do.

Use the event handler When HTTP_REQUEST to capture the header containing the cookie, store it in a variable. Log it or not and then compare it to the string data-group and take an action.

so here is something that you can work off of. You need to pre-configure a pool, a string based data-group. The syntax might be off as I quickly threw it together but you should be able to work off of this and get it going.

when CLIENT_ACCEPTED {  
    log local0. "[IP::client_addr]: HTTP Client Connected"
}
when HTTP_REQUEST {
    set Found_Cookie"[HTTP::header value Cookie]"
     Your choice to log this or not 
     log local0. "Detected Cookie as $Found_Cookie"
    if { [class match $Found_Cookie contains Cookie_String_Data_Group } {
          log local0. "Cookie matches data-group and this connection will be rejected"
          reject  
    }
      } else {
       log local0. "Cookie does not match the reject list Allowing connection"
       pool XYZ
}