TCP SYN Flood

Summary

TCP SYN Flood is a type of denial-of-service (DoS) attack that exploits the TCP handshake process by overwhelming a target server with a flood of SYN requests, causing resource exhaustion and service disruption.

Key Characteristics

• Targets the TCP three-way handshake by sending numerous SYN packets without completing the connection.
• Consumes server resources by leaving connections half-open, leading to denial of legitimate service.
• Often uses spoofed IP addresses to mask the attack source and complicate mitigation.
• Can be launched from a single source or as part of a distributed denial-of-service (DDoS) attack.
• Primarily affects application layer services relying on TCP connections, such as web servers and mail servers.

Defensive Controls

• Implement SYN cookies to validate legitimate connection requests without reserving resources prematurely.
• Configure firewalls and intrusion prevention systems (IPS) to detect and block abnormal SYN traffic patterns.
• Rate-limit incoming SYN packets to prevent overwhelming the server.
• Deploy load balancers and traffic scrubbing services to absorb and filter attack traffic.
• Use network segmentation and redundancy to reduce the impact of attacks.

Related Security Solutions

Network firewalls, intrusion detection and prevention systems (IDS/IPS), DDoS mitigation services, SYN cookie mechanisms, and traffic filtering appliances are commonly employed to defend against TCP SYN Flood attacks.