Programs such as nmap -o need the root user to perform, so that when the program execution rights determined by the executive authority? (or run the options program will automatically try to obtain root?)
But by a buffer overflow can elevate privileges, can put up a normal user to root, then get the root of the shell perhaps program permissions to carry out the instructions is the root (that is to say a normal user can perform a emits root instruction program, the program itself is already should be a good design authority?)

That I am now very contradictory, authority is executed application or have set good? (I can tell) trouble people