A program has been discovered that infects a critical Windows system executable and stays dormant in
memory. When a Windows mobile phone is connected to the host, the program infects the phone’s boot loader
and continues to target additional Windows PCs or phones. Which of the following malware categories BEST
describes this program?

A.
Zero-day

B.
Trojan

C.
Virus

D.
Rootkit

Explanation:
A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and
runs against your wishes. Viruses can also replicate themselves. All computer viruses are man-made. A simple
virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus
is dangerous because it will quickly use all available memory and bring the system to a halt. An even more
dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
Some people distinguish between general viruses and worms. A worm is a special type of virus that can
replicate itself and use memory, but cannot attach itself to other programs.