What is an RDDoS Attack?
An RDDoS (Reflected Distributed Denial of Service) attack is a sophisticated type of DDoS (Distributed Denial of Service) attack. It involves sending falsified requests with the source IP address spoofed to appear as the victim’s IP. This results in a flood of responses directed at the victim’s system, causing it to become overwhelmed and unable to provide normal services.
Unlike typical DDoS attacks, RDDoS attacks can achieve a higher amplification effect, making them particularly damaging to the target network. The primary goal is to disrupt the normal operations of websites, servers, and network equipment.
Mechanisms of RDDoS Attacks
IP Spoofing
Attackers manipulate the source IP address in packet headers to make it appear as though the packet originates from the target. This trickery ensures that the reflecting servers send their responses directly to the victim.
Utilizing Reflector Servers
Common network services like DNS, NTP, SSDP, and SNMP are often exploited as reflectors in RDDoS attacks. These servers inadvertently amplify the attack by sending larger responses back to the victim, significantly increasing the traffic volume.
Amplification Effect
The hallmark of RDDoS attacks is the amplification effect, where small requests result in significantly larger responses. This enables attackers to generate a large-scale traffic flood using minimal resources, effectively leading to service denial.
Types of RDDoS Attacks
DNS Amplification Attack
In a DNS amplification attack, the attacker sends a request with the target’s IP address to a DNS server. The server, in turn, sends back a large response, causing the victim to receive a deluge of traffic.
NTP Amplification Attack
This attack exploits the ‘monlist’ feature of NTP servers, which returns a list of recent clients. A small request can result in a response hundreds of times larger, overwhelming the victim’s network.
SSDP Amplification Attack
Attackers utilize UPnP-supported devices by sending SSDP requests, leading to a significant amount of traffic directed at the victim’s network.
SNMP Amplification Attack
By exploiting SNMP, attackers can send requests that generate large responses, causing a sharp increase in network traffic.
Preventing RDDoS Attacks
Blocking IP Spoofing
Implementing BCP 38, which involves source address verification, can prevent spoofed IP packets from traversing the network. Filtering unauthorized IP addresses at the network edge routers is also crucial.
Securing Reflector Servers
Limiting unnecessary open resources on services like DNS, NTP, and SSDP, and applying the latest security patches can mitigate the risk of being exploited in RDDoS attacks.
Utilizing Network Firewalls and IPS/IDS
Detecting abnormal traffic patterns and blocking malicious requests through firewalls or Intrusion Prevention Systems (IPS) can help defend against RDDoS attacks. Deep Packet Inspection (DPI) solutions can analyze and filter malicious traffic effectively.
Traffic Monitoring
Implementing systems to detect unusual traffic in real-time and using alert features for bandwidth overages can provide early warning and enable timely responses to potential attacks.
Deploying CDN and Cloud-Based DDoS Protection
Cloud-based solutions and Content Delivery Networks (CDNs) can distribute large traffic loads, minimizing the impact of an RDDoS attack and ensuring service continuity.
Responding to RDDoS Attacks
Traffic Filtering and Blocking
During an attack, specific ports or IP addresses can be blocked through network equipment. Access Control Lists (ACLs) or firewall configurations can be adjusted to filter out malicious traffic.
Traffic Diversion
Using cloud-based DDoS mitigation services allows for the separation of legitimate requests from attack traffic, reducing the impact on the victim’s network. CDNs can also help diffuse the attack.
Collaboration with ISPs and Security Firms
Working with Internet Service Providers (ISPs) to block the source of the attack and utilizing security firms’ DDoS response solutions can provide real-time defense.
Strengthening Server and Network Resources
Expanding bandwidth, implementing load balancing, and creating a distributed server environment can help withstand RDDoS attacks by preventing resource exhaustion.
Developing an Emergency Response Plan
Establishing a clear process for immediate action during a DDoS attack is vital. Regular drills to test and improve response procedures can enhance readiness.
Final Thoughts on RDDoS Attacks
RDDoS attacks pose a significant threat due to their amplified traffic generation capabilities. Comprehensive preventive measures and robust response strategies are essential to safeguard services against such attacks. Implementing stringent security policies and maintaining continuous monitoring can effectively protect against the risks associated with RDDoS attacks.