Unlock the Potential Of Syn to Enhance Cybersecurity
By Tom Seest
At BestCybersecurityNews, we help entrepreneurs, solopreneurs, young learners, and seniors learn more about cybersecurity.
SYN flood attacks are a type of denial-of-service attack that takes advantage of the three-way TCP protocol handshake (SYN, SYN-ACK, and ACK). When servers’ SYN backlog fills up too rapidly, legitimate clients cannot receive services.
Each SYN connection requires a Transmission Control Block data structure on the server that uses memory; without receiving an ACK packet from its client, this could leave half-open connections that use up more resources than needed to keep running.
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All computers use Transmission Control Protocol/Internet Protocol (TCP/IP). When starting up a TCP conversation with a server, a computer sends out a SYN packet as part of its handshake; upon reply from the server comes back another SYN-ACK packet which establishes the connection. Unfortunately, some hackers use SYN floods to flood ports with SYN packets, effectively overwhelming legitimate traffic streams and closing off access.
Attackers have various tools available to them when conducting SYN attacks, including direct and distributed methods. Direct methods involve one device with an actual IP address sending malicious packets directly toward their target network; this makes tracking attribution and mitigating it simpler. Meanwhile, botnets allow attackers to launch more complex attacks that are harder to detect or stop.
SYN flooding involves sending numerous TCP-SYN packets with fake TCP-SYN headers from an attacker to an affected server until all its resources have been consumed, leaving no open connections for legitimate users to connect to and causing a denial of service (DoS) attack against them.
An SYN attack can hit any type of server that handles TCP connections, from web servers and email servers to virtual private servers (VPS) and cloud-based servers. Attackers could target web servers in order to generate DoS attacks that temporarily take down websites or infrastructure servers like firewalls, routers, and load balancers to disrupt communication and steal information.
Syn-attacks are among the most dangerous forms of DDoS attacks, yet they are notoriously hard to identify and stop. Luckily, there are ways to guard against them – such as employing several best practices listed here:
Increased server backlog sizes may reduce the probability that any fraudulent SYN packets will be rejected; however, this strategy may prove ineffective against high-volume attacks.
SYN cookies offer another effective defense measure. This technique assigns each connection request with a unique identifier that allows filtering of unwarranted packets; however, this approach can significantly slow network performance and may even be circumvented by attackers who spoof their source IP addresses.
Countermeasures are tools and strategies used to prevent, avert, or minimize potential threats against computers, servers, operating systems, networks, or information systems. Countermeasures typically come in the form of software or hardware; examples include firewalls, antivirus software, and spyware removal programs. Countermeasures are utilized across a wide variety of scenarios in order to guard against network attacks as well as malware threats.
Cyber attacks pose an imminent risk to any organization and can have devastating repercussions, including theft of customer data and disruption of operations, as well as fraud or identity theft. Therefore, companies must take measures against such attacks with countermeasures.
There is an array of countermeasures available; however, not all are successful at blocking all threats. Therefore, selecting the most effective ones for each situation requires selecting them with care and using the knapsack approach in which the implementation costs and effectiveness of a collection of measures are measured before selecting one or more subsets as budget allows.
The law of countermeasures permits States that have been injured by another State’s international unlawful action to take unlawful measures against it in order to force compliance with international obligations (such as ceasing any unlawful behavior). While this doctrine is widely applicable in cyber operations, scholars have raised doubts as to its applicability in cyberspace operations.
As organizations embrace new technologies to expand their reach, streamline business processes, gather and analyze data, communicate with clients and employees more efficiently, and communicate more securely, they face increasing cyber threats. Successful companies make threat mitigation their top priority to minimize disruptions and potential losses.
Mitigation involves adopting a multilayered security posture that prioritizes mission impact to reduce the probability of attacks succeeding, for instance, implementing tiered administrative access systems with procedures designed around secure resetting credentials can help ensure high-value assets don’t fall prey to threat actors targeting privileged accounts and transferring risks onto someone with expertise and resources to deal with them effectively.
SYN flood attacks can be devastating to servers that provide online services such as web and email. They interrupt normal service while also potentially incurring financial damages. A SYN attack works by abusing the three-way handshake of Transmission Control Protocol (TCP), creating numerous half-open connections on servers to tie up resources while depriving legitimate users of access. A single attacker or even an entire network of infected computers (known as a botnet) may launch such attacks.
Installing an intrusion detection system and firewall, along with using SYN cookies that allocate unique identifiers for every connection and rate limiting (limiting the maximum number of SYN packets that can be sent out per server ), are among the many strategies available to prevent SYN flood attacks.
An alternative way of protecting against a SYN flood attack is increasing the size of the SYN backlog, which stores half-open connections. Each OS allows certain memory for this backlog; when its limit has been reached, one of its oldest connections will be deleted to make room for a new connection request – this method may prove effective against low-volume attacks.
Increase the retry count for SYN handshake, forcing an attacker to attempt establishing a TCP connection multiple times before receiving an RST packet from your server and making it more difficult for an attacker to guess their sequence number, an essential component of TCP handshakes.
One way is to configure your firewall so it blocks direct attacks from attackers’ own IP addresses or with fake IPs; these methods may be harder for malicious attackers to detect; nonetheless, they can help deter high-volume attacks from taking place. Finally, network gear designed specifically to mitigate SYN attacks such as load balancers is an essential way of combatting these types of attacks; such equipment handles TCP SYN/SYN-ACK/ACK handshakes which help alleviate flooding of production servers from SYN flooding attacks.
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