source: https://www.securityfocus.com/bid/1175/info

UltraBoard 1.6 (and possibly all 1.x versions and the new beta Ultraboard 2000) are vulnerable to this Denial of Service attack.

A remote user is able to expend all of the available resources of the webserver by using a specially-devised request to the CGI. This request causes a fork, which will then consume the processor time and memory of the server.

http:://target/ultraboard.pl?request=Session=../UltraBoard.pl%00%7c