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.