Journal 6:Learning about virus, trojan and worm

VIRUS
A computer virus is a computer program that can copy itself and infect a computer. A true virus can only spread from one computer to another.The virus can also be carried by removable disk medium such as floppy disk and USB drive. Viruses can increase their chances of spreading to other computers by infecting files on a network file system.

Type of virus: Boot viruses: These viruses infect floppy disk boot records or master boot records in hard disks.

Boot viruses load into memory if the computer tries to read the disk while it is booting. Examples: Form, Disk Killer, Michelangelo, and Stone virus

Program viruses: These infect executable program files, such as those with extensions like .BIN, .COM, and .EXE. The virus becomes active in memory, making copies of it and infecting files on disk. Examples: Sunday, Cascade

Multipartite viruses: A hybrid of Boot and Program viruses. They infect program files and when the infected program is executed, these viruses infect the boot record. Examples: Invader, Flip, and Tequila

TROJAN
Trojan is a term used to describe malware that appears to the user, to perform a desirable function and had unauthorized access to the user's computer system. It does not self-replicating but require interaction with a hacker to fulfill their purpose.
Types of Trojan:
Remote Access Trojans

Most of these Trojans are often a combination of the other variations described below. The idea of these Trojans is to give the attacker a total access to someone's machine and therefore access to files.

Keyloggers
The only thing they do is logging the keystrokes of the victim and then letting the attacker search for passwords or other sensitive data in the log file. Most of them come with two functions like online and offline.

Destructive
The only function of these Trojans is to destroy and delete files. Trojan can be activated by the attacker or sometimes works like a logic bomb and starts on a specific day and at specific hour.

WORMS
Computer worm is a program which copies itself across a network. A computer worm can spread without a host program, although some modern computer worms also use files to hide inside.

Types of worms:
Email Worms
Spread through infected email messages which may contain an attachment or a link of an infected website.

Instant Messaging Worms
These worms spread via instant messaging applications by sending links of infected websites to the entire contact list.

Internet Worms
Internet worm tries to gain access to any vulnerable machine either by scanning the Internet and/or using the local operating system.