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What is a DDoS Attack?

Working in information technology nowadays entails addressing the possible security threats that face businesses of all sizes, industries, and geographies. The field of cybersecurity is extensive and diverse, covering both subtle data theft techniques like spear phishing and larger brute-force moves like distributed denial of service (DDoS) attacks.Learning about cyber risks like DDoS assaults can help you become a more valuable part of a team working on information systems. Let's dive deep into the subject of DDOS, which is considered one of the most dangerous attacks in cyber security.

What Does DDoS Mean?

A Denial of Service (DoS) attack is an attempt to render a system unavailable to the intended user(s), for example, by blocking access to a website. This is performed when an attacker successfully exhausted all available network or system resources, resulting in a server slowness or crash. Whenever multiple sources are coordinating to achieve the attacker's goals in the DoS attack, it is known as DDOS.

How Does DDoS Attack Work?

DDoS, or distributed denial of service, is a cyber attack that blocks victims from accessing systems and network resources, thereby interrupting IT services.

By flooding an internet service or website with unwanted traffic from several computers, a DDoS attack attempts to make it unavailable.

An attacker must propagate malicious software to vulnerable devices in order for a DDoS attack to succeed, primarily through corrupted emails and attachments.

This will result in the creation of a botnet, which is a network of infected PCs.

The attacker can then train and control the botnet, directing it to overwhelm a specific site with traffic until the point where the botnet's network stops working, effectively taking the site offline.

Botnets come in a variety of shapes and sizes, with the most current, Mirai, containing an estimated 380,000 bots.

Mirai, a malware that gained notoriety in 2016, had the ability to infect unsecured internet of things devices including DVRs and IP cameras.

What are DDoS Attack Types?

To begin with, there are three major categories of attacks that make up the ecosystem's backbone:

  • Application Layer Attacks
  • Protocol Attacks
  • Volume-based attacks

DDOS Types

Figure 1. DDOS Types

1. Application Layer

Low-and-slow attacks, GET/POST floods, attacks on Apache, Windows, or OpenBSD vulnerabilities, and more are all included. The purpose of these attacks, which are made up of seemingly genuine and harmless requests, is to crash the webserver, and the size is measured in Requests per second (Rps).

Do Network Layer and Application Layer DDoS Attacks Differ?

DDoS attacks at the network layer exhaust the available bandwidth in order to overwhelm the target. Intrusion Prevention Systems and Next-Generation Firewalls are used to defend them largely at the network edge. Even with DDoS defenses in place, a large-scale bot network can quickly overwhelm the edge.

DDoS attacks on the application layer do not target network bandwidth. Rather, they attack the application (Layer 7 of the OSI model) that is running the service that end users are attempting to access. The server, server application, and back-end resources are the primary targets in this regard. The purpose of these assaults is to deplete the resources of a given service, slowing it down or even shutting it down.

In comparison to network-layer DDoS attacks, application-layer DDoS attacks are also more difficult to detect and counteract. CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart) is a popular method used to prevent application-layer DDoS attacks.

Some types of application-layer attacks are explained below.


Slowloris makes an effort to keep as many connections to the target web server open as possible, and to keep them open for as long as possible. It does so by establishing connections with the target web server and submitting a partial request. It will send more HTTP headers on a regular basis, but it will never complete the request. Affected servers will keep these connections open until they reach their maximum concurrent connection pool, at which point they will block further connection requests from clients.

Slowloris DDoS Attack

Figure 2. Slowloris DDoS Attack

HTTP Flood

HTTP Flood is a Distributed Denial of Service (DDoS) attack in which the attacker uses seemingly legitimate HTTP GET or POST requests to attack a web server or application.

These attacks are usually a group of volumetric attacks of Internet-connected computers (Zombie Army), each of which is hijacked for malicious purposes, with the help of malware such as 'Trojan Horses'.

HTTP flood attacks can be classified into two types:

1. HTTP GET attack

Numerous computers or other devices are coordinated to send multiple requests for photos, files, or other assets from a targeted site in this type of attack. When the target is overloaded with incoming requests and responses, legitimate traffic sources will suffer denial-of-service.

2. HTTP POST attack

When a form is submitted on a website, the server must receive the incoming request and push the data into a persistence layer, most often a database, in this sort of attack. When compared to the amount of computing power and bandwidth required to send the POST request, the process of handling the form input and running the appropriate database commands is comparatively intensive. This attack takes advantage of the gap in relative resource consumption by sending a large number of post requests to a single server until the server's capacity is reached and a denial-of-service occurs.

HTTP Flood Attack

Figure 3. HTTP Flood Attack

2. Protocol Attacks

Protocol attacks, also known as state-exhaustion attacks, disrupt operations by consuming too much server resources and/or network equipment resources such as firewalls and load balancers.

Protocol attacks make use of flaws in the protocol stack's layer 3 and layer 4 to render the target unreachable.

SYN floods, fragmented packet attacks, Ping of Death, are some examples of protocol attacks. This form of attack uses server resources or intermediate communication infrastructures like firewalls and load balancers and is measured in packets per second (PPS).

Syn Flood

An SYN Flood is a type of Denial-of-Service (DDoS) attack that can be used against any system that is connected to the Internet and provides Transmission Control Protocol (TCP) services (e.g. web server, email server, file transfer).,

  • The most common type of DDoS attack in the Internet world
  • It's pretty easy
  • If necessary precautions are not taken, 100Mb with 2Mb line systems that have the line can be disabled If necessary precautions are not taken, 100Mb line can be disabled with 2Mb line systems
  • It's as easy to defend as it is to attack
  • Usually accomplished using fake IP addresses

SYN Flood Attack

Figure 4. SYN Flood Attack

Ping of Death

The ping of death (PoD) is a type of denial-of-service attack in which an attacker uses oversized data packets to crash, destabilize, or freeze computers or services. This type of DoS attack typically targets and exploits legacy vulnerabilities that have been addressed by companies. Ping floods, which target systems by overloading them with (ICMP) packets, are also a threat to unpatched systems. Since the late 1990s, modern computers have been safeguarded against ping of death attacks.

An Internet Control Message Protocol (ICMP) echo-reply message, sometimes known as a "ping," is a network tool that operates similarly to sonar in that it sends out a "pulse" and the "echo" from that pulse provides the operator information about the environment. The source machine receives a response from the targeted machine if the connection is working.

While some ping packets are quite short, IPv4 ping packets are substantially larger and can be up to 65,535 bytes in size. Because some TCP/IP systems are never intended to handle packets larger than the maximum, they are vulnerable to packets larger than that.

When an attacker sends a maliciously big packet to the target, it is broken into segments, each of which is smaller than the maximum size limit. When the target machine tries to rejoin the pieces, the total exceeds the size limit, resulting in a buffer overflow, which can cause the machine to freeze, crash, or reboot.

This exploit can be carried out via ICMP echo, but it can also be carried out using any device that sends an IP datagram. TCP, UDP, and IPX transmissions are all included.

Ping of Death Attack

Figure 5. Ping of Death Attack

3. Network-centric or Volume-based Attacks

UDP floods, ICMP floods, and other spoofed-packet floods are some types of volume-based attacks. The purpose of the assault is to saturate the bandwidth of the targeted site, and the size of the attack is measured in bits per second (bps).

UDP Flood

A denial-of-service attack in which a high number of User Datagram Protocol (UDP) packets are sent to a targeted server in order to overload that device's ability to process and react. UDP flooding can potentially exhaust the firewall protecting the targeted server, resulting in a denial-of-service attack on genuine traffic. A UDP flood's main goal is to saturate the Internet pipe.

A UDP flood is a type of volumetric Denial-of-Service (DoS) attack in which the attacker sends IP packets including User Datagram Protocol (UDP) packets to random ports on the host. The host searches for applications connected with these datagrams in this form of attack. When none are detected, the host sends the sender a �Destination Unreachable� packet. The system becomes inundated and hence unresponsive to valid traffic as a result of being bombarded by such a flood.

There are no internal safeguards in place to slow down the rate of a UDP flood. As a result, UDP flood DOS attacks are extremely dangerous because they may be carried out with very little resources.

 UDP Flood Attack

Figure 6. UDP Flood Attack

Ping Flood

Ping flood, also known as ICMP flood, is a typical DoS technique in which an attacker overwhelms a victim's computer with ICMP echo requests, also known as pings, to bring it down.

The attack entails sending a large number of request packets to the victim's network, knowing that the network will respond with an equivalent amount of reply packets.

Using specialized tools or scripts, such as hping and scapy, to bring down a target with ICMP requests is another option.

This puts a burden on the network's incoming and outgoing channels, consuming a substantial amount of bandwidth and resulting in a denial of service.

Ping Flood Attack

Figure 7. Ping Flood Attack

NTP Amplification

NTP Amplification is a type of DoS attack that generates garbage traffic using a publicly accessible NTP (Network Time Protocol) server.

The amplification effect can be leveraged for the attack by making short requests (e.g., MON GETLIST) to an Open NTP server, which results in a response that is dozens of times larger (the amplification effect). The criminal sends similar queries with the victim server's IP address as the request's source. As a result, the affected server's network is clogged with unwanted UDP traffic, making valid NTP queries and responses impossible to filter.

The recommended safeguards are the same as those employed in the event of a UDP flood.

NTP Amplification Attack

Figure 8. NTP Amplification Attack

What is Use of DDoS attacks?

The basic purpose of a DDoS assault is to make your website inaccessible by utilizing botnets. Botnets are essentially an army of malware-infected connected devices. Because of this army, your website's server becomes overburdened and runs out of available bandwidth. The majority of the time, the attack does not compromise your data or violate any security parameters.

There are many grounds for a distributed denial of service attack, but today we'll look at the top six motivation reasons for DDoS attacks.

1. Competition

In fact, nearly half of the businesses that responded to a recent poll stated they suspected their competitors were undertaking DDoS assaults to disrupt services. After all, if your competitor's website is unavailable, all traffic will be directed to yours. Additionally, your competition�s brand image is tarnished, giving positive associations to your company instead.

2. Hacktivism

DDoS attacks aren't always about stealing information. It can be used to express a strong point of view - any point of view. Using the Internet to express your opinion can have a greater and faster impact than attending a demonstration or strike in person. DDoS is frequently used to demonstrate support or opposition to a particular topic. It could be political (see below), but also for/against businesses or banks, ethical concerns, or even an online game.

3. All about Politics

DDoS attacks, which are a subset of reason #2, can also occur between countries or governments. The Internet is the most recent battleground. Government websites may be targets of DDoS attacks. While the sites could have been targeted by apolitical hackers, many people feel that governments and political parties frequently use the DDoS approach to attack others.

4. Revenge

This circumstance could affect organizations, individuals, and governments, and is a common cause of DDoS attacks. Attacks are employed to seek revenge on your enemy, not necessarily to express an opinion. There's no need for you to get your hands dirty.

5. A Step Towards Something Bigger

According to Amazon, the greatest DDoS attack ever recorded was neutralized in early 2020 - with a peak traffic level of 2.3 Tbps, the most ever recorded, according to ZDNet. Prior to February of 2020, the previous greatest DDoS attack was in March of 2019, when NetScout Arbor successfully handled a 1.7 Tbps attack.

A hacker could be planning something fresh, as in the previous two situations, or they could be using the attack as a diversion from a larger attack, trying to avoid detection. This is one instance where the attack could be utilized for a security breach in an indirect manner.

6. For Fun

There isn't always a rhyme or reason as to why DoS or DDoS attacks occur.

There is a common misperception that all attacks have a specific cause. This, however, is just not true. Hacking into a system or a website, no matter how big or tiny provides an adrenaline rush for many hackers.

Are DDoS Attacks Dangerous?

The risk of a distributed denial-of-service attack (DDoS) poses a serious threat to company continuity. As businesses have become increasingly reliant on the Internet and web-based applications and services, availability has become just as important as power.

DDoS is a threat to businesses that rely on the availability, such as commerce, financial services, and gambling. DDoS assaults also target mission-critical business tools used by your company to run its day-to-day operations, including email, salesforce automation, CRM, and a variety of others. Other industries, such as manufacturing, pharmaceuticals, and healthcare, also have internal web properties that supply chains and other business partners rely on for day-to-day operations. Today's sophisticated cyber attackers are after all of these things.

What is the Difference Between DoS and DDoS attacks?

A denial-of-service (DoS) attack floods a server with traffic, effectively shutting down a website or resource. A distributed denial-of-service (DDoS) assault is a DoS attack that floods a targeted resource with several computers or machines. Some of the differences between DOS and DDOS are listed below.

1. Ease of detection/mitigation

Because a DoS originates from a single site, it is easy to identify and terminate the connection. In truth, a capable firewall can accomplish this. A DDoS attack, on the other hand, originates from several faraway places, concealing its source.

2. Attack speed

A DDoS attack can be deployed significantly faster than a DoS attack that originates from a single place because it originates from several locations. The increased assault speed makes detection more d

3. Traffic volume

Because a DDoS assault uses numerous remote machines (zombies or bots), it may send significantly bigger volumes of traffic from multiple locations at the same time, overwhelming a server quickly and evading detection.

4. Method of execution

A DDoS attack uses a command-and-control (C&C) server to coordinate many hosts infected with malware (bots), resulting in a botnet. A DoS attack, on the other hand, usually employs a script or tool to carry out the attack from a single machine.

5. Source(s) tracing

Because a botnet is used in a DDoS assault, finding the real origin is far more difficult than tracing the origin of a DoS attack, resulting in additional damage or potentially a disastrous result.

What is the most Powerful DDoS Attack?

Amazon said its AWS Shield service mitigated the largest DDoS attack ever recorded, stopping a 2.3 Tbps attack in mid-February 2020

 Live DDOS attacks on May 15, 2021 around the world

Figure 9. DDOS attacks on May 15, 2021 around the world

How Do You Detect a DDoS Attack?

The most challenging part of a DDoS attack is that no warnings are given. Some large hacking groups will issue threats, however, the majority of the time, an attacker will simply transmit the instruction to attack your site without any warnings.

If you don't regularly surf your site or if you do not have good monitoring systems, you don't realize something is incorrect until people complain. You might not realize it's a DDoS attack at first, assuming instead that your server or hosting is down. You examine your server and run some simple checks, but all you see is a lot of network traffic and resources that are all used up. You can look to see if any apps are running in the background, but there will be no obvious issues.

Several hours can pass between the time you recognize it's a DDoS assault and the time it takes to alleviate the damage. This means several hours of lost service and revenues, resulting in a significant reduction in your revenue.

The most efficient strategy to counteract a DDoS attack is to know what's going on as soon as the attack starts. There are a number of indicators that a DDoS attack is ongoing:

  • Over the course of y seconds, an IP address performs x requests.
  • Due to service disruptions, your server responds with a 503 error code.
  • A ping request's TTL (time to live) expires.
  • Employees will notice slowdown concerns if you use the same connection for internal software.
  • The use of log analysis tools reveals a significant increase in traffic.

What is a Zero Day DDoS Attack?

When the word is used for common protocols, it refers to a DDoS attack that takes advantage of previously unknown security flaws. When applied to well-known software, the term alludes to security flaws that the developers were previously unaware of. When a DDoS attack is carried out utilizing fresh new methods that have never been utilized before, it is often referred to as zero-day.

Does VPN Stop DDoS?

A VPN will not be able to completely prevent a DDoS attack. No one can, in fact. A VPN, on the other hand, can keep an attack from causing serious damage to your company. You can shield your actual servers from being attacked by using remote VPN servers. If a DDoS attack hits your remote servers, you can simply switch to another, more stable server.

Does Changing IP Stop DDoS?

When a large-scale DDoS assault is underway, changing the server's IP and DNS name can halt the attack. If the attacker is on the lookout, they may start sending traffic to your new IP address as well. If changing the IP fails, you can call your internet service provider (ISP) and request that they block or reroute the malicious traffic.

What is a DDoS Attack in Simple Words?

Consider a road. Let's pretend it's a two-lane road. It performs well; it is robust, secure, and dependable. You drive on it every day with no problems since it fulfills its function.

The city constructed that route because they have a fair estimate of how many cars will use it during the day.

Consider what would happen if a sudden event caused hundreds of cars to try to use that road at the same time. You attempt to take the onramp, but you are unable to do so once you reach the freeway. The road is completely jammed with traffic, and you'll be late if you make it to your destination at all.

A DDoS attack is essentially the same thing.

 A DDoS attack is similar to a road jammed with traffic

Figure 10. A DDoS attack is similar to a road jammed with traffic

What are the Methods of Preventing DDoS Attacks?

Here are a few things you can do to safeguard your websites and web apps from various types of DDoS attacks and help keep your website online at all times.

1. Increase bandwidth

Making your hosting infrastructure �DDoS resistant� is one of the most basic steps that can be taken to protect against DDoS attacks. Essentially, this means preparing enough bandwidth to handle traffic spikes due to cyber attacks.

Please keep in mind, however, that buying more bandwidth is not a complete solution for mitigating DDoS attacks. When you increase bandwidth, you raise the bar that attackers must clear before launching a successful DDoS attack, but you should always merge this with other mitigation tactics to fully protect your website.

2. Make use of a CDN solution, and even better, a multi-CDN solution.

CDN providers provide a wide variety of cybersecurity tools and features to keep hackers at bay. They also provide complimentary SSL certificates. Furthermore, when you add your website to these providers, DDoS protection is enabled by default to reduce attacks on your server network and application.

The reasoning behind this is that when you use a CDN network, all malicious requests targeting L3/L4 that do not access via ports 80 and 443 are automatically filtered out thanks to the CDN's port protocol.

3. Put in place DDoS protection at the server level.

Some web hosts provide server-level DDoS mitigation tools as part of their service. Because web hosting companies do not always provide this feature, you should check with your web host. Some businesses provide it as a free service, while others charge a fee for it. It all depends on the hosting provider and plan.

4. Prepare for DDoS attacks by fearing the worst.

Preparing for a cyberattack in advance allows you to respond quickly before the attack begins to harm your website.

A good incident response plan will include a list of coworkers who will deal with the attack. It also describes how the system will prioritize resources in order to keep most apps and services operational, potentially preventing your business from collapsing. Finally, you can plan how to contact the Internet Service Provider that is assisting the attack, as they may be able to completely stop it.

5. Use a hybrid or cloud-based solution.

When you switch to hybrid or cloud-based services, you will almost certainly have access to unlimited bandwidth. Many DDoS-affected websites are those that operate with limited resources. Switching to a cloud-based solution could really help you stay safe.