Final answer:
A malicious code covertly placed in a harmless program to perform unauthorized acts is known as a Trojan horse. Hackers distribute these programs to gain unauthorized access or disrupt systems, with governments also participating in similar cyber activities for espionage or warfare.
Step-by-step explanation:
The type of malicious code described, where unauthorized code is placed within a seemingly harmless program, and executes an unauthorized act such as destroying your hard disk, is known as a Trojan horse. This term comes from the story of the ancient Greek wooden horse that was used to infiltrate Troy. Unlike viruses, which can replicate themselves, a Trojan horse relies on users to install them or run them inadvertently.
Hackers use a variety of deceptive techniques to distribute Trojan horses, including disguising them as legitimate software. Cyber criminals and hackers can employ these to gain unauthorized access to systems, which can be used for stealing information or causing disruption.
Cybersecurity is a major concern as various organizations, including governments and militant groups, have been known to use hacking tactics to engage in cyber warfare. This can involve stealing secret intelligence, causing disruption in communication networks, and spreading disinformation.