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  • Writer's pictureRACHIT YADAV

What is a DOS Attack Denial of Service


After a short period of decline in incidences, denial of service (DoS), and Distributed denial of service attacks (DDoS) have become rampant once more. Whenever there is a major internet security incident, it mostly means that a DDoS attack occurred. These cybercriminals often target websites, personal accounts, servers, and other services to overload its internet traffic until the victim’s system becomes impassive to legitimate requests.

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What Is a Denial-Of-Service Attack?

A denial-of-service attack or DoS attack is a type of cyber-attack that occurs when an attacker seeks to render a computer or other networks inaccessible to its authorized users by momentarily or permanently interrupting the normal operations of a host linked to the Internet. Simply put, a denial-of-service (DoS) attack occurs when a cybercriminal prevents an authorized user from retrieving their personal data or files.

Typically, in a DoS attack, a single or group of computers are used to launch an attack. When these attacks are launched, they negatively affect an extensive array of services, including online accounts, private data, emails, websites, and other platforms that depend on the compromised computer or network.

How Do Denial of Service Attacks Work?

A denial of Service attack is often achieved using TCP and UDP packets. In a DoS attack, the perpetrators flood the user’s system with illegal traffic or service requests to inundate its resources and stop it from executing intended tasks.

A DoS attack can target distinct computers or a whole network system. These attacks can be costly for a company, both in terms of finance and timewise, until their services and other affected resources are restored or become accessible.

How to Tell if You are Experiencing a DoS Attack

The following are some pointers of the symptoms of a DoS attack often appear as a non-malicious accessibility problem. The most effective method of identifying and detecting a DoS attack is through network traffic







monitoring and testing. Network traffic can be scrutinized through an intrusion detection system or a firewall. The network manager or the owner of the device may even establish some instructions that create warnings when an irregular traffic load is detected and also recognize the source of the traffic or leaves network packets that match a certain criterion.

What Is the Most Common Form of DoS attacks?

DoS attacks are simple, yet effective. They can cause the most overwhelming loss to the target. There are different forms of DoS attacks. Different networks may be compromised by DoS attacks without being openly targeted. There are different forms of DoS, but the following are the most common ones:

Smurf Attack :

Here, the perpetrator exploits the broadcast address of a weak network by distributing spoofed packets that belong to the aimed device. Once the receivers of these spoofed packets respond, their Internet Protocol (IP) address is then flooded with those responses.

Considering the fact that a particular Internet Broadcast Address can sustain at most 255 hosts, a smurf attack works by intensifying each ping by 255. The outcome is that the network becomes slow to a level where it becomes difficult to use and discarded.

SYN Flood :

SYN Flood attacks occur when a cyber-attacker sends a request to connect to a server but does not complete the connection known as the three-way-handshake. This type of connection is a technique utilized in a Transmission Control Protocol (TCP)/IP network to form a connection between the server and local host/client. The outcome of the uncompleted handshake is that the network becomes overwhelmed with connection requests, making the connected port inaccessible to others. The malicious hacker will keep on sending requests, flooding all available ports until the authorized users are unable to connect.

Ping of Death or ICMP Flood :

ICMP flood attack is utilized to take misconfigured or unconfigured network and implement them in distributing spoof packets to ping all the system within that network. The ping of death attack is often merged together with ICMP flood.

Buffer Overflow Attacks :

This is one of the most widespread DoS attacks. A buffer is a momentary storage location in the random access memory (RAM) utilized for holding data to facilitate its use by the CPU prior to writing it back to the disc. Buffer has a size constraint and the aim of this type of attack is to overload it with more data than it can handle. Buffer overflow attacks allow a cyber-attacker to overflow a network address with traffic so as to make it discarded or unusable.

Teardrop Attack :

In a teardrop attack, the malicious hacker distributes fragments of an IP address packet to a targeted network. In turn, the network tries to reassemble these fragments to its initial packets. The method of assembling all these fragments to their initial packets wears out the system and as a result, it collapses. The system collapse or breakdown is due to the fact that the fields are created to obscure the system to the point where it is unable to assemble them together.

What Is Distributed denial of service (DDoS) Attack With Example?

Distributed denial of service (DDoS) attack is a malicious effort to render an online service or website inaccessible to users, typically by momentarily disrupting or appending the services of the host server. A Distributed denial of service attack naturally comprises of above 3 to 5 nodes on diverse networks, anything lesser may serve as a denial of service attack.

The aim of this attack is to make the website or online service impracticable. The traffic can involve fake packets, incoming mails, or requests for connections. Sometimes the target is compromised at a low level or threatened with a DDoS attack. This may be joined with blackmail and threats of more overwhelming attacks except the organization meets the set ransom. DDoS typically uses botnets to execute these malicious tasks.

What is a DDoS Botnet?

The term “botnet” refers to a group of hijacked internet-connected devices that are operated remotely from a Command & Control Center (C&C) by a malicious attacker. A botnet is a combination of the word network and robot and each compromised computer is referred to as a bot. These attacks characteristically comprise of unsecured IoT devices, PCs, smartphones, and sometimes resources from public cloud services.

A botnet is designed by a malicious hacker to achieve malicious tasks or execute illegal actions, such as stealing data, sending spam, fraudulently clicking on ads, ransomware, or Distributed denial of service (DDoS) attacks. Botnets work by allowing attackers to execute DDoS attacks by seizing the control of several computers and disrupting the traffic source of the traffic. It is often hard for security teams and other security applications to identify a DDoS attack until it is too late.

Malicious hackers use malware and other methods to infect a device, rendering it into a “zombie” in the perpetrator’s botnet. Although some malware may have an immediate effect on the device or network owners, DDoS botnet malware can have diverse stages of visibility. Some of this malware is intended to run mutely as a background while mutely awaiting commands from the “bot herder” or attacker. Other malware is intended to take absolute control of the device or network.

Self-circulating botnets engage other bots through a number of different pathways including Trojan horse malware, the exploitation of website weaknesses, and cracking scrawny verification to obtain remote admission. The moment access has been gained, all these infection techniques lead to the installation of malware on the aimed device. This grants the botnet operator a remote control of the device.

What Is the Difference Between DoS and DDoS Attack?

DDoS and DoS differ in that the latter uses a single internet connection (that is one internet-connected device or network) to flood the victim’s computer or other networks with malicious traffic, while the former uses multiple internet connections to render the victim’s network or device inaccessible to them. Hence, a DoS attack can be obstructed by blocking the single IP address.

DDoS attacks are the most powerful internet attacks and also the most difficult to detect. The reason being that they are introduced from several locations to hide their identities and prevent the victim from easily identifying the main source of the attack. As a result, it is unfeasible to distinguish between genuine and counterfeit network traffic.

Another difference between DDoS and DoS attacks lies in the volume of the attack being launched. While DDoS attacks give room for the cyber-attacker to introduce enormous volumes of traffic to the user’s computer or network, DoS cannot afford the attacker with such excesses. Additionally, you should also note that their mode of execution varies as well. While DoS attacks are executed using a script or DoS tool, such as Low Orbit Ion Cannon, DDoS attacks are usually launched using botnets or through the networks of the devices infiltrated by the attacker.

Broad Categories of DDoS and DoS attacks

Generally, there are two forms of DoS attacks including those that flood services and those that crash services. All other categories fall under these two. However, the most severe attacks are those that are distributed.

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