Explain the following malware a. Virus b. Trojan c. Worm d. Spyware

a. Virus: A computer virus is a type of malicious software program ("malware") that, when executed, replicates itself by modifying other computer programs and inserting its own code. Infected computer programs can include, as well, data files, or the "boot" sector of the hard drive. Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data, displaying political or humorous messages on the user's screen, spamming their contacts, logging their keystrokes, or even rendering the computer useless.

b. Trojan: A Trojan horse, or Trojan, is a type of malicious software that disguises itself as a normal file or program to trick users into downloading and installing malware. A Trojan can give a malicious party remote access to an infected computer. Once an attacker has access to an infected computer, it is possible for the attacker to steal data (like financial information or passwords), install more malware, modify files, monitor user activity (screen watching, keylogging, etc), use the computer in botnets, and anonymize internet activity by the attacker.

c. Worm: A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

d. Spyware: Spyware is software that aims to gather information about a person or organization, without their knowledge, and send such information to another entity without the consumer's consent, or asserts control over a device without the consumer's knowledge. It can collect almost any type of data, including personal information like internet surfing habits, user logins, and bank or credit account information. It can also interfere with user control of a computer by installing additional software or redirecting web browsers. Some spyware can change computer settings, which can result in slow internet connection speeds, un-authorized changes in browser settings, or changes to software settings.