The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser.
A web server is computer software and underlying hardware that accepts requests via HTTP or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message. A web server can also accept and store resources sent from the user agent if configured to do so.
In computing, a denial-of-service attack is a cyber-attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to a network. Denial of service is typically accomplished by flooding the targeted machine or resource with superfluous requests in an attempt to overload systems and prevent some or all legitimate requests from being fulfilled.
In computing, load balancing is the process of distributing a set of tasks over a set of resources, with the aim of making their overall processing more efficient. Load balancing can optimize the response time and avoid unevenly overloading some compute nodes while other compute nodes are left idle.
In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource.
A Smurf attack is a distributed denial-of-service attack in which large numbers of Internet Control Message Protocol (ICMP) packets with the intended victim's spoofed source IP are broadcast to a computer network using an IP broadcast address. Most devices on a network will, by default, respond to this by sending a reply to the source IP address. If the number of machines on the network that receive and respond to these packets is very large, the victim's computer will be flooded with traffic. This can slow down the victim's computer to the point where it becomes impossible to work on.
The Simple Service Discovery Protocol (SSDP) is a network protocol based on the Internet protocol suite for advertisement and discovery of network services and presence information. It accomplishes this without assistance of server-based configuration mechanisms, such as Dynamic Host Configuration Protocol (DHCP) or Domain Name System (DNS), and without special static configuration of a network host. SSDP is the basis of the discovery protocol of Universal Plug and Play (UPnP) and is intended for use in residential or small office environments. It was formally described in an IETF Internet Draft by Microsoft and Hewlett-Packard in 1999. Although the IETF proposal has since expired, SSDP was incorporated into the UPnP protocol stack, and a description of the final implementation is included in UPnP standards documents.
A botnet is a group of Internet-connected devices, each of which runs one or more bots. Botnets can be used to perform Distributed Denial-of-Service (DDoS) attacks, steal data, send spam, and allow the attacker to access the device and its connection. The owner can control the botnet using command and control (C&C) software. The word "botnet" is a portmanteau of the words "robot" and "network". The term is usually used with a negative or malicious connotation.
Internet security is a branch of computer security. It encompasses the Internet, browser security, web site security, and network security as it applies to other applications or operating systems as a whole. Its objective is to establish rules and measures to use against attacks over the Internet. The Internet is an inherently insecure channel for information exchange, with high risk of intrusion or fraud, such as phishing, online viruses, trojans, ransomware and worms.
In computer science and networking in particular, a session is a time-delimited two-way link, a practical layer in the TCP/IP protocol enabling interactive expression and information exchange between two or more communication devices or ends – be they computers, automated systems, or live active users. A session is established at a certain point in time, and then ‘torn down’ - brought to an end - at some later point. An established communication session may involve more than one message in each direction. A session is typically stateful, meaning that at least one of the communicating parties needs to hold current state information and save information about the session history to be able to communicate, as opposed to stateless communication, where the communication consists of independent requests with responses.
Single sign-on (SSO) is an authentication scheme that allows a user to log in with a single ID to any of several related, yet independent, software systems.
In computer networks, a reverse proxy is an application that sits in front of back-end applications and forwards client requests to those applications. Reverse proxies help increase scalability, performance, resilience and security. The resources returned to the client appear as if they originated from the web server itself.
NTP server misuse and abuse covers a number of practices which cause damage or degradation to a Network Time Protocol (NTP) server, ranging from flooding it with traffic or violating the server's access policy or the NTP rules of engagement. One incident was branded NTP vandalism in an open letter from Poul-Henning Kamp to the router manufacturer D-Link in 2006. This term has later been extended by others to retroactively include other incidents. There is, however, no evidence that any of these problems are deliberate vandalism. They are more usually caused by shortsighted or poorly chosen default configurations.
An application delivery network (ADN) is a suite of technologies that, when deployed together, provide availability, security, visibility, and acceleration for Internet applications such as websites. ADN components provide supporting functionality that enables website content to be delivered to visitors and other users of that website, in a fast, secure, and reliable way.
Prolexic Technologies was a US-based provider of security solutions for protecting websites, data centers, and enterprise IP applications from Distributed Denial of Service (DDoS) attacks at the network, transport, and application layers. It operated a DDoS mitigation platform and a global network of traffic scrubbing centers. Real-time monitoring and mitigation services were provided by a 24/7 security operations control center (SOCC). Prolexic indicated its DDoS mitigation services make websites, data centers and enterprise IP applications harder to take down via DDoS attacks.
Slowloris is a type of denial of service attack tool which allows a single machine to take down another machine's web server with minimal bandwidth and side effects on unrelated services and ports.
An algorithmic complexity attack (ACA) is a form of attack in which the system is attacked by an exhaustion resource to take advantage of worst-case performance. Worst-case performance through a back-end algorithm results in the exhaustion of the server, this creates algorithmic complexity vulnerabilities. According to Adam Jacobson and Dr. David Renardy, research scientists from Two Six Labs, "An AC Time vulnerability causes denial of service by exhausting CPU while AC Space vulnerabilities exhaust RAM or disk space." Examples of ACA attacks are zip-bombs, billion laughs, and ReDoS which are Malicious files aimed to render a program useless. Additionally, as stated by the Cybersecurity and Infrastructure Security Agency, a department within the Department of Homeland Security, “A denial-of-service (DoS) attack occurs when legitimate users are unable to access information systems, devices, or other network resources due to the actions of a malicious cyber threat actor. Services affected may include email, websites, online accounts, or other services that rely on the affected computer or network.” In other words, DoS attacks are a form of an attack in which a hacker can flood a server which outputs a denial-of-service error. ACA and DDoS attacks are forms of denial-of-service attacks in which the hacker can gain information through the Schemas files and its structure. In October 2022, Google released that they experienced the largest DDoS attack to date that took place in September 2017. Algorithmic complexity and its vulnerabilities are the main components that have given hackers ways to attack algorithms and its servers.
SlowDroid is the first denial of service attack which allows a single mobile device to take down a network server requiring minimal bandwidth. The attack has been created for research purposes by Enrico Cambiaso and Maurizio Aiello for the IEIIT Institute of the National Research Council of Italy and released as an Android application.
High Orbit Ion Cannon (HOIC) is an open-source network stress testing and denial-of-service attack application designed to attack as many as 256 URLs at the same time. It was designed to replace the Low Orbit Ion Cannon which was developed by Praetox Technologies and later released into the public domain. The security advisory for HOIC was released by Prolexic Technologies in February 2012.
The BlackNurse attack is a form of denial of service attack based on ICMP flooding. The attack is special because a modest bandwidth of 20Mbit/s can be effective for disrupting a victim's network.
