DOS Attack (Denial of Service Attack, DoS Attack)
A DOS Attack, or Denial of Service Attack, is an attack that seeks to render a computer, computer network, or service unusable by flooding it with data so the resources become unavailable to legitimate users. These attacks typically overwhelm a computer or a network by transmitting a large amount of data traffic requests, making it difficult or impossible to respond to legitimate traffic. DOS Attacks usually rely on sending crafted packets (pieces of code or data) from multiple sources in order to flood a system and force it to respond to the requests asynchronously, either crashing the system or consuming all of its resources.
The most common methods used to launch DOS attacks are the SYN Flood, ICMP Flood, and UDP Flood. In SYN Flood attacks, hundreds or thousands of requests for connections are made, but none of them are completed. The ICMP Flood attack sends massive amounts of ICMP (Internet Control Message Protocol) echo requests to the server, consuming all of its resources. Finally, UDP Floods send a large number of UDP (User Datagram Protocol) packets to the target, overwhelming it with data traffic.
DOS attacks can cause a variety of problems for an attacked computer or network, ranging from making it unusable to causing data loss and system corruption. The cost of a DOS attack can also be significant, as it can result in the loss of business opportunities (through service disruptions), hardware upgrades (to cope with the increased traffic), and hiring additional staff to handle security and recovery efforts.
In an effort to protect themselves against DOS attacks, organizations use a variety of techniques and strategies, including firewalls, intrusion detection systems, and rate limits for incoming data traffic. In addition, services such as CloudFlare offer web application firewalls that can detect and block DOS attacks before they affect an organization’s internet servers.
