Ben-smile Jokes2

MALWARE.

Malware is the collective name for software that has been designed to disrupt or damage data, software or hardware. There are several types of malware, such as viruses, worms and Trojans, which you’ll learn more about in the next few steps.

However, as malware has evolved, from its beginnings as demonstrations of prowess by individual programmers to sophisticated technologies developed by organised crime, the boundaries between the different categories are beginning 

Types of malware...

1. Viruses

The best-known type of malware is probably the virus, although many pieces of malware are called viruses they are nothing of the sort.

A virus is a piece of software that has been written to insert copies of itself into applications and data and onto crucial parts of a computer’s hard disk. Viruses are said to be self-replicating programs and date back as far as the early 1970s, but they only became well known with the advent of microcomputers and later, the internet.

Viruses attach themselves to specific applications on a computer and are activated when the program is first run. At that point, the virus may make a copy of itself on the hard disk and continue to run, or it may only run each time the application is used. Early viruses, relying on floppy disks for transmission, spread quickly as infected data disks were shared around an office, or pirated software was passed around a playground. Nowadays, viruses rely on devices such as flash memory cards or are transmitted through internet connections.

Although some viruses are not intended to cause harm, the majority of these programs are designed to harm users, by corrupting their data or attacking the operating system itself or providing an exploitable ‘backdoor’, giving attackers access to the computer. Even where no harm is intended, viruses consume memory, disk space and processing power

Worms

Another type of self-replicating malware is the worm; like a virus it is designed to make copies of itself; but unlike a virus, a worm is a standalone application.

Worms spread through network connections, accessing uninfected machines and then hijacking their resources to transmit yet more copies across the network.

There are four stages in a worm attack:

1. The first stage is when the worm probes other machines looking for a vulnerability that can be exploited to copy itself to.
2. The next stage is to penetrate the vulnerable machine by performing the operations for exploiting the vulnerability. For example, the worm might detect an open network connection, through which it can get the remote machine to execute arbitrary instructions.
3. In the third stage, the worm will download itself to the remote machine, and store itself there. This is often called the ‘persist’ stage.
4. In the next stage, the worm will propagate itself by picking new machines to attempt to probe.

Worms were invented as a curiosity and have even been suggested as ways of testing networks or distributing software patches across a network; however their drawbacks far outweigh their benefits. Even the most ‘benign’ worm consumes resources and can affect the performance of a computer system.

Trojans

The final major type of malware is the Trojan (or Trojan horse); named after the wooden horse that supposedly smuggled Greek soldiers into the ancient city of Troy.

A Trojan disguises itself as an entirely legitimate program (such as a screensaver), but behind the scenes it is causing damage – perhaps allowing someone else to gain control of the computer, copying personal information, deleting information, monitoring keystrokes, or using email software to pass itself on to other computers. Unlike viruses and worms, Trojans are not self-replicating, they rely on their apparent usefulness to spread between computers.

Some Trojans work in isolation. Some, however, rely on networks, either to transmit stolen information – such as passwords, bank account details or credit card numbers – or to act as back doors to compromised computers. They allow attackers to bypass the operating system’s security features and gain access to data or even control the machine over a network.