Updated August 19, 2023
Introduction to Denial of Service Attack
DoS or DDoS attack (Denial of service attack) is a cyber-attack meant to shut down machines or networks, to make it inaccessible to its intended users. DDoS attacks function by flooding the target with traffic, which results in denial of service. DDoS attacks may come from various sources, which makes it difficult to block attacks. Often Crime related DoS attacks target high profile sites such as banks, credit card payment. Thus, in short, DDoS is an attempt of attackers to prevent legitimate use of services.
What is a Denial of Service Attack?
Denial of service attack is a type of attack which comes from several sources that prevent the actual use of services. The History of DoS attacks starts when it was detected in Panix (world 3rd largest ISP in the world) that is in the year 1996, Panix was subject to Flood attack, which was later figured out by Cisco by the proper solution. Recently DDoS attacks have been seen in Arbor Networks which fell into a trap on March 5th, 2018 with a peak of 1.7 terabits per second, Secondly, on March 1st, 2018, Github faced the crisis with a peak of 1.35 terabits per seconds.
There are two types of DoS attacks as per they are characterized:
- Those who crash Services.
- Those who Flood Services.
Distributed Denial of Service
- The most common DoS attacks are distributed. Those are large scale attacks where the executioner uses more than one unique IP address or machine, where the attacks involve more than 3+ nodes on different networks, but some may or may not be DDoS attacks. As the incoming traffic flooding victim originates from various sources, it simply difficult to avoid those using filtering only, as sometimes it makes difficult to distinguish between legitimate traffic and malicious traffic. A few Examples of DDoS (Distributed Denial of Service) are Smurf, SYN flood.
- Application Layer networks, Literally Known as Layer 7 DDoS attack, where attackers target the application layer. The attack targets some specific functions of a website to disable them. Those application network attacks are often used to distract security breaches. It was recorded around 20 % attacks in the year 2013 for application-layer DDoS attacks. It may be less frequent occurring but it never has slowed down in terms of continuing attacks.
- Application Layer DDoS attacks are specifically done for disrupting targets and interfere with the database. An attack may look like the usual traffic, but it intends to harm a specific function or application.
How to Prevent Denial of Service Attacks?
Many defense techniques use the combination of attack detection, traffic classification that aimed at blocking suspicious traffic. There is a list of prevention and response tools mentioned below:
- Application Front end Hardware is intelligent hardware placed just before the network just before traffic reaches the servers. It has also been used in networks in conjunction. It works as data enter the servers and they classify they are dangerous.
- Key completion indicators are those approaches towards Denial of Service attacks against cloud applications, they mainly rely on identified path of value inside the application where it marks the legitimate traffic and monitors progress.
- Blackholing and sink holing are the other two factors which are the two approaches, where the traffic attacked to the DNS and ISP are sent to the null server space. Sink holing guides’ traffic to a proper IP address which gathers the traffic and rejects the bad suspicious traffic.
- IPS based prevention is most effective when the attacks have a signature associated with them. But as it’s a content recognition which cannot block behavior-based attacks.
- A DoS Defense system can block connection-based DoS attacks, having legitimate content but bad intent.
Importance of Denial of Service Attack
DDoS has evolved into the most complex and typical Denial of service attacks. However DDoS when based on political or other motives, forensic evidence is typically harder as the traffic may be legitimate or a reflection of attackers or direct flood attacks. Therefore there is a need for DDoS protection that blocks attacks and also identifies the type of attacks and alerts against future emerging threats.
How does it Work?
A DDoS attack needs a targeter to have control over a network to begin an attack on a target site. Computers & Internet of Things (IoT) devices are damaged by malware and suspicious virus turning them into separate bots, where the attackers have remote access to control the bots. As it has control has several bots called a botnet. So each IP address of a target is influenced by a botnet, then each bot responds by sending requests to the target, which results in denial of normal traffic. In DDoS attacks, the system is rigged and sends thousands of “introductions”. The servers review it and whichever is not recognized, it sends a response, waiting up to a moment to hear a reply from another end. When no reply is there, the system execution for attacks continues.
For Example, if we want to communicate with an eCommerce website to shop. The user system sends a small packet of information to the website. The packet works as a short introduction as it’s the user which says as hello and it requests permission to enter into the site. The server responds asking as it’s real and legitimate, then it connects accordingly.
DDoS attacks are rising as a threat this year and it has crossed 400 Gbps traffic volumes. The attack duration ranges from few minutes to hours which damages a certain target. These attacks use DNS or NTP servers and also allow small botnets to conduct bulk attacks. DDoS is rising on a large scale and rises on in terms of IoT and mobile devices. It’s more important to have a proper DDoS protection solution for preventing those attacks which hamper the target site on a large scale
This is a guide to Denial of Service Attack. Here we discuss the introduction and how to prevent denial of service attacks along with importance. You may also have a look at the following articles to learn more –