Explanation

• Viruses, Trojan horses, and worms are malicious software used to harm a computer system.
• A Trojan Horse is a program that allows the attacker to control the user's computer from a remote location.

Additional Information 

• The list below shows some of the activities that the attacker can perform using a Trojan horse:
  • ​Electronic money theft.
  • Modifying files on the user’s computer
  • Damage the user’s computer (crashing, blue screen of death, etc.)
  • Stealing sensitive data such as stored passwords, credit card information, etc.

• A worm is a malicious computer program that replicates itself usually over a computer network.
• A virus is a computer program that attaches itself to legitimate programs and files without the user's consent.
• A computer virus may be used to;
• Access private data such as user id and passwords.
• Display annoying messages to the user.
• Corrupt data on your computer.
• Log the user’s keystrokes.