Understanding DOS and DDOS Attacks: Prevention Strategies
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Chapter 1: Introduction to DOS and DDOS
Since the advent of the internet, individuals have sought ways to compromise systems. Attackers may aim to steal sensitive data or render a system inoperable. They often attempt to overwhelm resources by sending excessive requests to a target.
When an attacker employs a single source to disrupt services, this is referred to as a Denial of Service (DOS) attack. Conversely, if multiple sources are involved, it is termed a Distributed Denial of Service (DDOS) attack. Protecting against a DOS attack is relatively straightforward, as blocking the offending IP addresses can suffice. However, defending against DDOS attacks requires a more sophisticated approach.
This video titled "DOS and DDOS attack - Most simplest explanation" provides a clear and concise overview of these attack types and their implications.
Initial Steps for DDOS Defense
To effectively shield your services from DDOS threats, adopting a zero-trust strategy is vital. This approach involves identifying and minimizing vulnerable areas. Clients that exceed predetermined resource thresholds will face mitigation measures. Initially, you can establish limits for Transactions Per Second (TPS) and the maximum number of active sessions or sessions per IP address.
For more robust protection, it is crucial to understand common types of DDOS attacks:
- UDP Flood: This attack involves inundating a target with User Datagram Protocol (UDP) packets, overwhelming random ports. The target continuously checks for applications on these ports and responds with an ICMP ‘Destination Unreachable’ message when none are found. This process drains the host’s resources, leading to inaccessibility.
- SYN Flood: This attack exploits a weakness in the TCP handshake process. The attacker sends numerous SYN requests but either fails to respond to the SYN-ACK from the target or uses spoofed IP addresses. Consequently, the host system waits for acknowledgments, consuming resources until no new connections can be established, resulting in a DDOS condition.
- HTTP Flood: Here, attackers utilize seemingly legitimate HTTP GET or POST requests to overwhelm a web server or application. Unlike other methods, HTTP floods do not rely on malformed packets or spoofing, making them less bandwidth-intensive but still capable of causing significant disruption.
The video "How to Perform DOS Attack | Ethical Hacking and Penetration Testing" offers insights into the ethical considerations surrounding these attacks and how they can be tested responsibly.
Chapter 2: Prevention Strategies
To counteract various types of DDOS attacks effectively, tailored prevention strategies are essential:
- Volume-Based Attacks: For attacks characterized by high traffic volume, employing a blackhole strategy can be effective. This involves routing the source IP addresses to a null destination, preventing them from reaching actual services.
- Protocol-Based Attacks: To mitigate these attacks, it is advisable to deploy an Intrusion Prevention System (IPS) to identify anomalies and establish firewalls with SYN flood thresholds. Traditional firewalls may lack the capability to address these threats.
- Application-Based Attacks: Detecting application-layer attacks necessitates behavioral analysis since many are executed by bots. Implementing authentication measures or bot defense mechanisms can offer robust protection.
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