What is DOS Attack?
A DOS attack is a denial of service attack; in this attack, a computer sends massive traffic to a victim’s computer and shuts it down.
Dos attack is an online attack that makes the website unavailable for its users when done a website. This attack causes the server of a website connected to the internet to send a large amount of traffic.
How does a DoS attack work?
A DoS attack’s primary focus is to oversaturate a targeted machine’s capacity, resulting in a denial of service to additional requests. The multiple attack vectors of DoS attacks can be grouped by their similarities.
DoS attacks are divided into two categories:
Buffer overflow attacks
An attack type in which a memory buffer overflow can cause a machine to consume all available hard disk space, memory, or CPU time. This exploit often results in sluggish behavior, system crashes, or other harmful server behaviors, resulting in a denial of service.
Flood attacks
A malicious actor can oversaturate server capacity by saturating a targeted server with an overwhelming amount of packets, resulting in a denial of service. For most DoS flood attacks to be successful, the malicious actor must have more available bandwidth than the target.
Symptoms of Dos Attacks :
Atypically slow network performance such as long load times for files or websites
The inability to load a particular website such as your web property
A sudden loss of connectivity across devices on the same network
What is a DDoS attack?
A distributed denial-of-service (DDoS) attack is a malicious attempt to disrupt the regular traffic of a targeted server, service, or network by overwhelming the target or its surrounding infrastructure with a flood of Internet traffic.
How does a DDoS attack work?
DDoS attacks are carried out with networks of Internet-connected machines.
These networks consist of computers and other devices (such as IoT) that have been infected with malware, allowing them to be controlled remotely by an attacker. These individual devices are called bots (or zombies), and a group of bots is called botnets.
Once a botnet has been established, the attacker can direct an attack by sending remote instructions to each bot.
When the botnet targets a victim’s server or network, each bot sends requests to the target’s IP address, potentially causing the server or network to become overwhelmed, resulting in a denial-of-service to regular traffic.
Because each bot is a legitimate Internet device, separating the attack traffic from regular traffic can be difficult.
Symptoms of DDoS attack :
The most obvious symptom of a DDoS attack is a site or service suddenly becoming slow or unavailable. But since several causes — such as a legitimate spike in traffic — can create similar performance issues, further investigation is usually required. Traffic analytics tools can help you spot some of these telltale signs of a DDoS attack:
Suspicious amounts of traffic originating from a single IP address or IP range
A flood of traffic from users who share a single behavioral profile, such as device type, geolocation, or web browser version
An unexplained surge in requests to a single page or endpoint
Odd traffic patterns such as spikes at odd hours of the day or practices that appear to be unnatural (e.g., a point every 10 minutes)
Other, more specific signs of a DDoS attack can vary depending on the type of attack.
Types of DDOS ATTACKS:
Volume-based (volumetric) attacks are the “classic” ones that congest a target network’s bandwidth with a hefty amount of traffic packets.
Protocol attacks are aimed at exhausting server or firewall resources.
Application layer (layer 7 DDoS) attacks zero in on specific web applications rather than the whole network. These are particularly hard to prevent and mitigate and relatively easy to orchestrate.
Furthermore, dozens of sub-types fall into either one of the above generic groups but exhibit unique characteristics. Here’s a complete breakdown of the present-day DDoS attack methods.
1. SYN Flood
This attack exploits the TCP three-way handshake, a technique that establishes any connection between a client, a host, and a server using the TCP protocol. Typically, a client submits an SYN (synchronize) message to the server to request a connection.
When an SYN Flood attack is underway, criminals send many of these messages from a spoofed IP address. As a result, the receiving server becomes incapable of processing and storing many SYN packets and denies service to actual clients.
2. LAND attack
To perform a Local Area Network Denial (LAND) attack, a threat actor sends a fabricated SYN message in which the source and destination IP addresses are the same. When the server tries to respond to this message, it gets into a loop by recurrently generating replies to itself. This leads to an error scenario, and the target host may eventually crash.
3. SYN-ACK Flood
The logic of this attack vector is to abuse the TCP communication stage, where the server generates an SYN-ACK packet to acknowledge the client’s request. To execute this onslaught, crooks inundate the CPU and RAM resources of the server with a bevy of rogue SYN-ACK packages.
4. ACK & PUSH ACK Flood
Once the TCP three-way handshake has established a connection between a host and a client, ACK or PUSH ACK packets are sent back and forth until the session is terminated. A server targeted by this DDoS attack cannot identify the origin of falsified containers and wastes all of its processing capacity trying to determine how to handle them.
5. Fragmented ACK Flood
This attack is a knockoff of the ACK mentioned above & PUSH ACK Flood technique. It boils down to deluging a target network with a comparatively small number of fragmented ACK packets with a maximum allowed size, usually 1500 bytes each. Network equipment such as routers runs out of resources to reassemble these packets. Furthermore, fragmented packets can slip below the radar of intrusion prevention systems (IPS) and firewalls.
6. Spoofed Session Flood (Fake Session Attack)
Cybercriminals may forge a TCP session more efficiently to circumvent network protection tools by submitting a bogus SYN packet, a series of ACK packets, and at least one RST (reset) or FIN (connection termination) packet. This tactic allows crooks to get around defenses that only keep tabs on incoming traffic rather than analyzing return traffic.
7. UDP Flood
As the name suggests, this DDoS attack leverages multiple User Datagram Protocol (UDP) packets. For the record, UDP connections lack a handshaking mechanism (unlike TCP), so the IP address verification options are minimal. When this exploitation is in full swing, the volume of dummy packets exceeds the target server’s maximum capacity for processing and responding to requests.
8. DNS Flood
This one is a UDP Flood variant that specifically homes on DNS servers. The malefactor generates a slew of fake DNS request packets resembling legitimate ones that appear to originate from many different IP addresses. DNS Flood is one of the most brutal denial-of-service raids to prevent and recover from.
9. VoIP Flood
This common form of UDP Flood targets a Voice over Internet Protocol (VoIP) server. The multitude of bogus VoIP requests from numerous IP addresses drain the victim server’s resources and knock it offline at the end of the day.
10. NTP Flood (NTP Amplification)
Network Time Protocol (NTP), one of the oldest networking protocols tasked with clock synchronization between electronic systems, is at the core of another DDoS attack vector. The idea is to harness publicly-accessible NTP servers to overload a target network with a large number of UDP packets.
11. CHARGEN Flood
Similar to NTP, the Character Generator Protocol (CHARGEN) is an oldie whose emergence dates back to the 1980s. Despite this, it is still being used on connected devices such as printers and photocopiers. The attack comes down to sending tiny packets containing a victim server’s fabricated IP to devices with CHARGEN protocol enabled. In response, the Internet-facing devices submit UDP packets to the server, thus flooding it with redundant data.
12. SSDP Flood
Malefactors can exploit networked devices running Universal Plug and Play (UPnP) services by executing a Simple Service Discovery Protocol (SSDP) reflection-based DDoS attack. On a side note, SSDP is embedded in the UPnP protocol framework. The attacker sends small UDP packets with a spoofed IP address of a target server to multiple devices running UPnP. As a result, the server is flooded with requests from these devices to the point where it goes offline.
13. SNMP Flood (SNMP Amplification)
Tasked with harvesting and arranging data about connected devices, the Simple Network Management Protocol (SNMP) can become a pivot of another attack method. Cybercriminals bombard a target server, switch, or router with numerous small packets coming from a fabricated IP address. As more and more “listening” devices reply to that spoofed address, the network cannot cope with the immense quantity of these incoming responses.
14. HTTP Flood
When executing an HTTP Flood DDoS attack, an adversary sends ostensibly legitimate GET or POST requests to a server or web application, siphoning off most or all of its resources. This technique often involves botnets consisting of “zombie” computers previously contaminated with malware.
15. Recursive HTTP GET Flood
To perpetuate this attack, a malicious actor requests an array of web pages from a server, inspects the replies, and iteratively requests every website item to exhaust the server’s resources. The exploitation looks like a series of legitimate queries and can be challenging to identify.
16. ICMP Flood
Also referred to as Ping Flood, this incursion aims to inundate a server or other network device with numerous spoofed Internet Control Message Protocol (ICMP) echo requests or pings. The network responds with the same number of reply packets after receiving a certain number of ICMP pings. Since this capability to respond is finite, the network reaches its performance threshold and becomes unresponsive.
17. Misused Application Attack
Instead of spoofed IP addresses, this attack parasitizes legitimate client computers running resource-intensive applications such as P2P tools. Crooks reroute the traffic from these clients to the victim server to bring it down due to excessive processing load. This DDoS technique is hard to prevent as the traffic originates on real machines previously compromised by the attackers.
18. IP Null Attack
This is carried out by sending a slew of packets containing invalid IPv4 headers that are supposed to carry transport layer protocol details. The trick is that threat actors set this header value to null. Some servers cannot process these corrupt-looking packets properly and waste resources trying to work out how to handle them.
19. Smurf Attack
This one involves a malware strain called Smurf to inundate a computer network with ICMP ping requests carrying a spoofed IP address of the target. The receiving devices are configured to reply to the IP in question, which may produce a flood of pings the server can’t process.
20. Fraggle Attack
This DDoS technique follows a logic similar to the Smurf Attack, except that it deluges the intended victim with numerous UDP packets rather than ICMP echo requests.
21. Ping of Death Attack
To set this raid in motion, cybercrooks poison a victim network with unconventional ping packets whose size significantly exceeds the maximum allowed value (64 bytes). This inconsistency causes the computer system to allocate too many resources for reassembling the rogue packets. In the aftermath, the system may encounter a buffer overflow or even crash.
22. Slowloris
This attack stands out from the crowd because it requires very low bandwidth and can be fulfilled using just one computer. It works by initiating multiple concurrent connections to a web server and keeping them open for an extended period. The attacker sends partial requests and complements them with HTTP headers once in a while to make sure they don’t reach a completion stage. As a result, the server’s capability to maintain simultaneous connections is drained, and can no longer process references from legitimate clients.
23. Low Orbit Ion Cannon (LOIC)
Originally designed as a network stress testing tool, LOIC can be weaponized in real-world DDoS attacks. Coded in C#, this open-source software deluges a server with many packets (UPD, TCP, or HTTP) in an attempt to disrupt a target’s operation. This onslaught is usually backed by a botnet consisting of thousands of machines and coordinated by a single user.
24. High Orbit Ion Cannon (HOIC)
HOIC is a publicly accessible application that superseded the abovementioned LOIC program and has a much more enormous disruptive potential than its precursor. It can be used to submit many getting and HTTP POST requests to a server concurrently, knocking a target website offline. HOIC can affect up to 256 different domains at the same time.
25. ReDoS
ReDoS stands for “regular expression denial-of-service.” Its goal is to overburden a program’s regular expression implementation with instances of highly complex string search patterns. A malicious actor can trigger a frequent expression processing scenario whose algorithmic complexity causes the target system to waste extra resources and slow down or crash.
26. Zero-Day DDoS
This term denotes an attack that takes advantage of uncatalogued vulnerabilities in a web server or computer network. Unfortunately, such flaws are surfacing off and on, making prevention a more challenging task.
Top Best Tools for DDOS:
1) Solar Wind DDOS
SolarWinds DDoS Attack is a tool that can be used to perform a Distributed Denial of Service attack. This application can monitor the event log from numerous sources to find and detect DDoS activities.
Features:
This application can detect communication with control servers and commands.
It provides responses in real-time.
You can easily filter specific timeframes, IPs, or parameters.
The tool helps you to detect malicious activity between the command and control server.
PRTG network monitoring software is known for its advanced infrastructure management capabilities. The tool monitors IT infrastructure using technologies like SNMP, WMI, Sniffing, REST APIS, SQL and others.
Features:
PRTG can scan network segments by pinging defined IP ranges
It helps you to create web pages with up-to-date monitoring data in the desired design
Easy and flexible alerting
Multiple User Interfaces
Alerts you when it sees warnings or unusual metrics in your network.
3) LOIC (Low Orbit ION cannon)
LOIC (Low Orbit ION cannon) is open-source software used for DDoS attacks. This DDoS tool is written in C#. This tool sends HTTP, TCP, and UDP requests to the server.
Features:
LOIC is one of the free DDoS attack tools that helps you test the network’s performance.
It enables you to create a DDoS attack online against any site they control.
Loic does not hide an IP address even if the proxy server is not working.
It helps you perform stress testing to verify the system’s stability.
This does software can be used to identify DDoS programs that hackers may use to attack a computer network.
Link: https://sourceforge.net/projects/loic/
4) HOIC (High Orbit ION cannon)
High Orbit Ion Cannon is a free denial-of-service attack tool. It is designed to attack more than one URLs at the same time. This ddos tool helps you to launch DDoS attacks using HTTP (Hypertext Transfer Protocol).
Features:
You can attack up to 256 ddos websites at once.
It has a counter that helps you to measure the output.
This DDoS machine free tool can be ported over to Linux or Mac OS.
You can choose the number of threads in the current attack.
HOIC enables you to control attacks with low, medium, and high settings.
Link: https://sourceforge.net/projects/highorbitioncannon/
Sucuri uses advanced technology software like Web Application Firewall ( WAF) and Intrusion Prevention System ( IPS) to provide protection against DdoS Attacks. They constantly regulate your website traffic and rankings while increasing your website performance.
Features:
They block layers 3, 4, and 7 DDoS attacks.
It provides Malware and Hacks protection with a Web Application Firewall ( WAF )
They constantly regulate all the patch updates and server rules that protect your website.
They provide Protect Page Feature, which you can enable on certain sensitive websites by adding passwords, CAPTCHA, 2FA, etc.
It has an easy set-up as it only requires web server credentials and a DNS change.
6) HTTP Unbearable Load King (HULK)
HTTP Unbearable Load King (HULK) is a web server DDoS tool. It is one of the free ddos attack tools specifically used to generate volumes of traffic at a webserver.
Features:
It can bypass the cache server.
This tool helps you to generate unique network traffic.
HTTP Unbearable Load King (HULK) can be easily used for research purposes.
Link: https://packetstormsecurity.com/files/112856/HULK-Http-Unbearable-Load-King.html
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7) DDoSIM (DDoS Simulator)
DDoSIM (DDoS Simulator) is a tool that is used to create a distributed denial-of-service attack against a target server. It is written in C++ and can be used on the Linux operating system.
Features:
This ddos tool indicates the capacity of the server to handle application-specific DDOS attacks.
It enables you to create full TCP connections to the target server.
DDoSIM provides numerous options to perform a network attack.
TCP connections can be flooded on a random network port.
Link: https://sourceforge.net/projects/ddosim/
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8) PyLoris
PyLoris is a software product for testing network vulnerability by performing Distributed Denial of Service (DDoS) attack online. It helps you to manage ddos online and control poorly manage concurrent connections.
Features:
It provides easy to use GUI (Graphic User Interface).
This tool enables you to attack using HTTP request headers.
It has the latest codebase (collection of source code used to build a particular software system).
You can run PyLoris using Python script.
This tool supports Windows, Mac OS, and Linux.
It provides an advanced option having a limitation of 50 threads, each with a total of 10 connections.
Link: https://motoma.io/pyloris/
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9) OWASP HTTP POST
The OWASP (Open Web Application Security Project) HTTP Post software enables you to test your web applications for network performance. It helps you to conduct denial of service from a single DDoS machine online.
Features:
It allows you to distribute and transmit the tool with others.
You can freely use this tool for commercial purposes.
OWASP HTTP POST helps you to share the result under the license it provides.
This tool enables you to test against the application layer attacks.
It helps you to decide the server capacity.
Link: https://owasp.org/projects/
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10) RUDY
RUDY is a short form of R-U-Dead-Yet. It is one of the free ddos attack tools that helps you to perform the DDoS attack online with ease. It targets cloud applications by starvation of sessions available on the web server.
Features:
This is a simple and easy tool.
It automatically browses the target ddos website and detects embedded web forms.
R-U-Dead-Yet enables you to conduct HTTP DDoS attack using long-form field submission.
This tool provides an interactive console menu.
This DDoS free attack tool automatically identifies form fields for data submission.
Link: https://sourceforge.net/projects/r-u-dead-yet/
11) Tor’s Hammer
Tor’s hammer is an application-layer DDoS software program. You can use this ddos online tool to target web applications and a web server. It performs browser-based internet request that is used to load web pages.
Features:
It allows you to create rich text markup using Markdown (a plain text formatting syntax tool).
Tor’s Hammer automatically converts the URL into links.
This app uses web server resources by creating a vast number of network connections.
You can quickly link other artifacts in your project.
It holds HTTP POST requests and connections for 1000 to 30000 seconds.
Link: https://sourceforge.net/projects/torshammer/
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12) DAVOSET
DAVOSET is software for committing DDOS attacks via abuse of any website functionality. This command line tool helps you to commit distributed denial of service attacks without any hassle.
Features:
It is one of the ddos tools that provides support for cookies.
This DDoS attack for free software provides a command-line interface to perform an attack.
DAVOSET can also help you to hit attack using XML external entities (attack against an app that parses XML input).
Link: https://packetstormsecurity.com/files/123084/DAVOSET-1.1.3.html
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13) GoldenEye
GoldenEye tool conducts a DDoS attack by sending an HTTP request to the server. It utilizes a KeepAlive message paired with cache-control options to persist socket connection busting.
Features:
This tool consumes all the HTTP/S sockets on the application server for the DDoS attack.
It is one of the ddos tools which is easy to use app written in Python.
Arbitrary creation of user agents is possible.
This DDoS program randomizes GET, POST to get the mixed traffic.
Link: https://sourceforge.net/projects/goldeneye/
