SYN Flood is a type of denial-of-service attack in which a malicious actor sends a large number of requests to a server, but does not acknowledge the connection, leaving it half-open. This is usually done with the intention of consuming server resources, which can lead to denying other users access to the server. In this article, we will discuss how a SYN Flood attack works, why it is so dangerous, how to identify its signs, and what measures can be taken to prevent it from taking over a system. SYN Flood is one of the most common attacks on the Transmission Control Protocol/Internet Protocol, and it works by exploiting a vulnerability in the way TCP/IP handles incoming connection requests. To establish a connection, the client first sends a SYN packet to the server. The server then responds to the original packet with a SYN/ACK packet, and the client returns an ACK packet to the server to acknowledge receipt of the packet. In the case of a SYN Flood attack, the dynamic of the connection changes, leaving it half-open. The attacker sends a large number of SYN packets to the target server, with a fake source IP address. The server responds to each SYN packet by sending a SYN-ACK packet back to the supposed source, waiting for a final ACK packet to complete the three-way handshake and establish a connection. Since the source IP address is fake, the ACK packet is never received, leaving the server with a large number of half-open connections that consume resources and ultimately overload the system, causing a denial of service. There are two types of SYN Flood attacks: spoofed attacks and distributed attacks. In a spoofed attack, the malicious client spoofs the IP address on each SYN packet it sends to the server. In a distributed attack, the client employs a botnet that distributes the source of malicious packets across numerous machines. SYN Flood attacks are dangerous because they can cause a denial of service, rendering a target server or network unavailable to legitimate users. They can be launched from a large number of sources, either by a single attacker using multiple computers or by a group of attackers using a network of infected computers. Signs of a SYN Flood include high network traffic, unresponsive servers, increased CPU usage, network connectivity problems, and increased error rates. To prevent a SYN Flood attack, measures such as using SYN cookies, network segmentation, load balancing, network visibility, and network security devices can be taken. The Mirai Botnet used SYN Flood, among other flooding techniques, to compromise over 600,000 Internet of Things devices and launch one of the most damaging DDoS attacks in history. In conclusion, SYN Flood attacks can be a serious threat to the security of a network, and it is important to be aware of the signs and take the necessary steps to prevent them.
This Cyber News was published on heimdalsecurity.com. Publication date: Wed, 08 Feb 2023 11:27:02 +0000