Question

Show how a malicious user can miuse a setuid program to gain root access

Answer 1

suppose you downloaded an unknown .apk file from browser which has transparent icon and no name, if you try to install that file to your machine, that may ask you for root access if your machine is rooted and if your machine is not rooted it will try to root your machine and access the root permission...........
I suggest you to not to download any apk file unless you know what you are doing,,,,

((machine=your android smartphone))
with regards
A.D. Singh