How to Mitigate a DDoS Attack?

DDoS Attack  :
Distributed Denial of Service Attack is a sophisticated cyber attack, which is performed on digital assets, such as servers and computer systems. Primary aim of an attacker to executed this is to permanently shut down the target system or crash it for a long period of time, so that operations to be performed by user can be disturbed. In this, a single machine is targeted and data packets are sent from multiple botnet machines, which are controlled by a single attacker’s system. 
Attacker forwards the command to botnets, which are infected by malicious codes. Further, these botnets continuously forwards the malicious data packets to targeted system. When the packet handling limit of targeted system is exhausted, it leads it to shut down or crash permanently. This is one of the most dangerous cyber attack, which can cause organizations to face huge financial loss.  

Mitigation mechanisms to prevent DDoS Attack  :
To prevent such attacks and to maintain data confidentiality, integrity, availability and authenticity, below listed mitigation mechanisms can be configured on network –

1. Intrusion Detection System –
   This is an advance security mechanism, which is configured in the network to monitor and analyze the data packets transmitted over it. This security device works on the principle of predefined parameters, which are used to maintain security. These predefined parameters are inclusive of techniques, which can be used by an attacker, to breach security. Whenever a predefined parameter is matched with current scenario of the network, this security system alerts the administrator and executes the defined security action. 
   To prevent DDoS attack, this device must be configured in the network, as whenever, a large number of data packets will be forwarded towards a single system from a spoofed IP address, it will automatically alerts the authorized person, so that appropriate action can be taken and targeted digital asset can be secured.
2. Use of Load Balancers  –
   In large organizational network, load balancers can be configured, as it will distribute the traffic over network, which will allow the servers to easily to process each data packet. Also, additional resources can be reserved using this mechanism, which will be allocated, when large volume of data packets is detected over network. 
   These resources can be inclusive of extra RAM and processing power, which can be used by server machines to analyze each user request. This mitigation mechanism is mostly configured in cloud infrastructures to maintain the state of virtual machines running on a single physical system.
3. Blackhole Routing –  
   This routing technique is configured in a network to forward all the malicious and unwanted traffic to a null point, from where it cannot be forwarded further and dropped. This mechanism is not used very frequently, as it consumes high volume of RAM, processing power and bandwidth. To configure this routing, a static route is enabled on the routers deployed in the network. 
   After detection of spoofed data packets from botnet network, overall network traffic is forwarded to static destination address and is finally dropped at that location. This results to mitigate the DDoS attack, as target system is secured from large amount of traffic.
4. Firewall and anti-spoof solution – 
   Firewall is the most basic security mechanism, which must be configured in the network and anti-spoof solution should be installed on it. This mechanism will monitor each and every data packet transmitted over network and check its source and destination address. In addition to this, anti-spoof solution will increase its analysis capability, as it will enable it to differentiate between legitimate and illegitimate data sources. 
   If any malicious and suspicious data packet is detected, it will drop it at the border or  network, which will lead to secure the other devices from cyber attack. Both software and hardware firewall must configured in network, as it will ensure that only authorized users are able to request and utilize network resources.
5. Network Isolation –  
   Overall network should be divided by creating virtual local area networks, as it will aid to distribute network traffic in an effective manner. With this, each department in an organization will be provided with its own local area network. 
   If a distributed denial of service attack is executed on network of a single department, then local area network of other departments can be isolated and remaining digital assets can be secured from data breach. In addition to this, organization can continue to perform their business operations and provide resources and services to their authorized users. This configuration can be performed by any organization regardless of its size.
6. Content Delivery Network (CDN) –                                                                                                                                                                                 A CDN is a distributed network of servers that cache and deliver web content to users based on their geographic location. It can also help in preventing DDoS attacks by absorbing and filtering out malicious traffic before it reaches the targeted server.
7. Traffic filtering –                                                                                                                                                                                                                  Network administrators can filter out traffic from known malicious IP addresses, ports, and protocols using tools such as Access Control Lists (ACLs) and IP reputation services. This can help in reducing the amount of unwanted traffic and protecting the targeted server.
8. Bandwidth throttling –                                                                                                                                                                                                   Bandwidth throttling is the practice of limiting the amount of traffic that can pass through a network connection. By limiting the bandwidth of a connection, network administrators can prevent a DDoS attack from overwhelming the network and affecting other legitimate traffic.
9. Cloud-based DDoS protection –                                                                                                                                                                                Cloud-based DDoS protection services are designed to detect and mitigate DDoS attacks in real-time. These services can help in reducing the impact of an attack by filtering out malicious traffic before it reaches the targeted server.
10. Server hardening –                                                                                                                                                                                                               Network administrators can harden their servers by disabling unnecessary services, applying security patches and updates, and configuring firewalls and intrusion detection/prevention systems. This can help in reducing the attack surface of the server and making it more difficult for attackers to exploit vulnerabilities.