From The Register
"A vulnerability involving an obscure UDP protocol might permits crackers to obtain remote control of Unix workstations, security experts have warned.
Security firm ProCheckUp has issued an advisory warning that anonymous XDMCP connections allow remote attackers to obtain a remote console identical
to a local X-Windows session, using a command enabled by default on most Unix boxes."
March 18, 2002
Back Orifice for Unix flaw emerges from obscurity