What is DDoS Attack? How to Stop a DDoS Attack?

What is a distributed denial-of-service (DDoS) attack?

DDoS attacks are a primary concern in cybersecurity today.

A distributed denial-of-service (DDoS) attack, as the name suggests, is a malicious attempt to disrupt normal traffic of a targeted server, service or network by overwhelming the target resources or its surrounding infrastructure with a flood of fake Internet traffic. 

Distributed denial-of-service attacks target websites, online web applications, and other network resources. The primary purpose is to overwhelm them with more traffic than the server or network can accommodate.

DDoS attacks achieve persistence by utilizing multiple compromised computer systems as sources of fake Internet traffic.

The traffic can consist of incoming messages, connection requests or fake packets which cybercriminals can employ to cause a denial of service for the legitimate users of the targeted resource.

Unlike other ransomware and phishing campaigns, a DDoS attack is like a traffic jam clogging up with a highway, preventing regular traffic from arriving at its desired destination.

How does a distributed denial-of-service (DDoS) attack work?

A DDoS assault requires an attacker to gain control over a server or other network resource to initiate an attack.

The DDoS attack tools developed by hackers identify other vulnerable system and network resources such as IoT devices and gains controls over them by either infecting the systems with malware or through bypassing the authentication controls.

The attacker then has remote control over the group of bots (also known as zombie computers), which is called a botnet.

Once a botnet has been established, the attacker is able to direct the infected devices by sending updated malicious instructions to each bot via command and control servers.

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When the botnet targets the IP address of a victim, each bot will respond by sending malicious commands to the target source, potentially causing the server or network to overflow capacity, resulting in a denial-of-service to normal traffic.

Distributed denial-of-service (DDoS) attacks are popular and profitable outbreaks which offer a less complicated attack mode than other forms of cyber-crimes. There are three basic categories of DDoS attack:

• Volume Based Attacks: Include ICMP floods (also known as Ping Floods), User Datagram Protocol (UDP) floods and other spoofed-packet floods. This type of attacks use high traffic to saturate the bandwidth of the targeted site and magnitude is measured in Bits per second (BPS).
• Protocol Attacks: Includes synchronization packets (SYN floods), Ping of Death, fragmented packets, Smurf DDoS attacks and more. This type of attack focuses on exploiting server resources, intermediate communication equipment such as firewalls and load balancers, and the magnitude is measured in Packets per second (PPS).
• Application Layer Attacks: The application based attacks are considered as the most sophisticated and destructive type of attacks which includes HTTP GET/POST floods, Windows and OpenBSD vulnerabilities and more. Comprised of seemingly innocent and legitimate requests, the goal of these attacks is to crash the web applications/server, and magnitude is measured in Requests per second (RPS).

Different types of DDoS attacks fall into categories based on the flow of online traffic and vulnerabilities being targeted.

What are the most popular types of DDoS attack?

Here is a list of some common types of DDoS attacks:

User Datagram Protocol (UDP) Flood

A UDP flood, as the name suggests, is a session-less authentication protocol that floods a target with User Datagram Protocol (UDP) packets. The main aim of the attack is to flood random ports on a remote host with a deluge of UDP packets.

This causes the host to repeatedly check for the application listening at that port and when no application is found, it tends to reply with an ICMP ‘Destination Unreachable’ packet. This process attenuates host computer/network resources, which can ultimately lead to inaccessibility.

SYN Flood

An SYN flood DDoS attack exploits the weakness in the TCP connection sequence (also known as “three-way-handshake”). The host machine receives an SYN request (synchronization packets) to initiate a TCP connection.

The server acknowledges the request by sending an SYN-ACK response to the initial host, which then closes the connection.

In an SYN flood scenario, the requester sends multiple SYN requests, but either does not respond to the host’s SYN-ACK response or sends the SYN requests from a spoofed IP address.

Either way, the targeted computer/server continues to wait for the response for each of the requests, binding resources until no new connections can be made, and ultimately resulting in a denial of service to legitimate traffic.

HTTP Flood

In HTTP flood (Hyper Text Transfer protocol) DDoS attack, the hacker exploits seemingly legitimate HTTP GET/POST requests to crash the web server or applications. HTTP floods use less bandwidth than other attacks to bring down the targeted site or server.

ICMP Flood

Similar in principle to the UDP flood attack, an ICMP (Ping) flood overwhelms the target server or network with ICMP Echo Request (ping) packets, generally sending packets as fast as possible without waiting for responses.

This type of DDoS outbreak can utilize both incoming and outgoing bandwidth, since the victim’s machines will often attempt to respond with ICMP Echo Reply packets, resulting in a significant overall system slowdown.

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DDoS attacks do not attempt to breach your security perimeter directly but are often used as a disguise or smokescreen for other attacks and malicious activities.

This distributed denial-of-service (DDoS) assaults are the most noticeable of attacks owing to the network downtime, crashes, and shutdowns they cause.

These glitches like downtimes and poor system performance cause financial losses and damage the reputation of the organizations.

It may take several months and hefty costs for the enterprises to recover from the impacts of such attacks.

Distributed denial-of-service (DDoS) attacks are becoming a popular tactic for most type of cyber-attackers including hacktivists, cybervandals, and extortionists.

Conclusion

Nowadays, cybercriminals have learned to make their malware infections more adaptable, resilient and dangerous than ever before. While no silver bullet can provide a shield against all cyber risks at the same time. Hence, how can we prevent DDoS attack?

First, we must upgrade our cyber defense systems and DDoS mitigation techniques to more effectively guard against botnets or specific application vulnerability attacks, as well as to respond in a timely and robust manner to prevent any future intrusions.

Note* - We recommend ITL Total Security and Malware crusher, among the best reputed anti-malware software which will provide effective DDoS protection solution and guard your machines, servers or IoT devices against Trojans, hijackers, adware and other network volumetric attacks.

They are fully loaded with many useful features like Invalid Registry Cleaner, Real-Time Protection, Web Protection, Live updates, and many more to protect your system from all kinds of disarray and keep you safe always.

Tips to Prevent virus and malware from Infecting Your System: