How does a denial of service attack affect a business?

A Denial of Service (DoS) attack, unlike other security compromises such as basic attacks, identity attacks, and malicious code, are created to target a server or other network component with the intent to make the site unavailable to users. Typically, in a DoS attack, the primary motive is to deny the victim access to a certain resource and this attack will "prevent legitimate users of a service from accessing that service" (Carnegie Mellon).

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There are several ways a DoS attacks can be initiated, but they usually aim to:

• Consume limited (or scarce) resources
• Modify or destroy configuration information
• Physically destruct or modify network components

Consuming bandwidth is also another way to target in a DoS attack. Unlike attacks where the goal is to steal data or gain unauthorized access to the data, the objective of a DoS attack is to cripple or disable a server or network.

How Does a Denial of Service Attack Work?

When a denial of service attack is launched, this act is carried out by flooding the site with requests to overwhelm it, then it ignores the server's response. As a result, the traffic is increased tremendously and the system is unable to handle this vast level of activity. The attacking computer is programmed to ignore each of the server's responses, and the line is kept “busy” with each request since the server (or network) is waiting for a response that doesn’t come. This makes the server unavailable for other requests that come in.

With a successful attack, the server runs out of resources and performance is significantly decreased or lost completely. Another way an attacker can approach a DoS attack is to ping a computer using Internet Control Message Protocol (ICMP).

The return IP address is spoofed to be the address of the victim rather than that of the attacker and the server will respond to these computers, tying up valuable internet resource and network space.

What is a Distributed Denial of Service Attack?

Another type of DoS attack is the Distributed Denial of Service. This is accomplished by the attacker using a large number of computers to accomplish the attack. Typically, an attacker will find a way to access a large computer that has plenty of memory and a fast Internet connection. After a computer is selected and entry gained (essentially hijacked), the attacker loads software onto this computer that will scan thousands of other computers in search of vulnerabilities in their systems.

If any susceptibility is discovered in another computer, the handler installs malicious software on these computers. These accessed computers are referred to as "zombies" because they are virtually directed what to do as they are controlled by an outside source. The attacker will designate the handler to direct all zombie computers to target a specific server with requests, which will lead to a rapid DoS attack. The attack is massive since thousands of zombies can have been made and used to achieve this and wreak a lot of damage.

DoS attacks can have serious consequences since this act can virtually disable a server or computer network. If an organization relies on their computer and network resources for their primary business, such as an e-commerce site, a denial of service attack can cause serious problems affecting the business. DoS attacks can result in a significant loss of both money and time, reducing both productivity and profitability.

It is important to know that not all disruptions to a website are due to a DoS attack, it could be the site was taken down temporarily for maintenance or there may be some other type of temporary tech issues going on.