Denial of Service

What is a Denial of Service?

A Denial of Service (DoS) attack is a malicious activity meant to shut down a system or a network, making it inaccessible to intended users.

Hackers launch DoS attacks by flooding target systems with traffic or sending information that causes a network to crash. In both situations, the DoS attack deprives legitimate users, such as employees, members, and account holders, of the system resources or services.

A DoS attack is analogous to a group of idlers crowding a shop’s entry door, making it hard for legitimate customers to enter, thus disrupting operations.

Key Takeaways

  • A DoS attack makes shuts down systems and networks, making it inaccessible to intended users.
  • Cyber attackers send massive traffic to flood a target system. They also send information that triggers a system to crash.
  • Some examples of DoS attacks include flooding services, crashing services, and distributed denial of service (DDoS)
  • Some vendors sell advanced DoS-as-a-service products as security tools, but hackers use them for unauthorized activities
  • Use DoS protection tools and implement a disaster recovery plan to prevent and respond to DoS attacks

Types of DoS Attacks?

There are three main methods in DoS attacks:

  1. Flooding DoS Services: flooding DoS occurs when attackers send too much traffic for the server to buffer. The attack causes the system to slow down and eventually stop. Some examples of flooding services include:
    1. Buffer Overflow Attacks: In this attack, hackers send more traffic to a network address than a system can handle.
    2. ICMP Flood: This attack leverages misconfigured network devices by sending spoofed packets that ping devices on the network. The attack, also known as smurf or ping of death, triggers a network to amplify the traffic.
    3. SYN Flood: An attacker sends a request to connect to a server, but does not complete the handshake. Instead, the requests continue until all open ports are saturated with traffic, and none are left for legitimate users to connect to
  2. Crashing DoS Services: These attacks exploit vulnerabilities that cause a system or service to crash. An attacker sends input that takes advantage of existing bugs in a target system. The incident destabilizes the system, which eventually crashes, preventing user access.
  3. Distributed Denial of Service (DDoS): A DDoS attack occurs when multiple computers plan simultaneous DoS attacks on a single target. Instead of attacking a system from one location, hackers can leverage many sites (multiple computers or bots) to breach a network. Some of the DDoS capabilities include:
    • The distribution of attack hosts in a DDoS attack allows hackers to leverage many machines to execute a disruptive attack.
    • It is difficult to detect the attack source or location due to the random distribution of attack sources
    • It is challenging to recover from DDoS attacks

Who are the Victims of DoS?

In most cases, victims of DoS attacks are web servers and applications of high-profile organizations like eCommerce, payment gateways, banking, media companies, and government agencies.

Impact of DoS Attacks?

Most frequently, a DoS attack does not result in the theft or loss of information and other assets. However, the incident disrupts regular system services, which can cost the victim a great deal of money and time to recover.

Depending on the severity of a DoS attack, system resources may be offline for 24 hours, several days or even weeks. A survey by Kaspersky Lab revealed that one in five DoS attacks could last for days or weeks.

During a DoS attacks, employees and customers are not able to access network resources. In the case of eCommerce sites, customers cannot purchase products, leading to a loss of revenues and reputation.

DoS as a Service

Some vendors provide booter or stresser services that have simple web-based front ends and accept payments over the web. Sellers market and promote denial-of-service-as-a-service products as stress-testing tools. However, hackers use the program to perform unauthorized DoS attacks. The sophisticated attack tools allow technically unsophisticated attacks to launch successful DoS breaches. 

How Can I Detect and Prevent DoS Attacks?

Symptoms of DoS attack include unusually slow network performance and unavailability of some websites. A sudden loss of connectivity across devices on the same network is also an indicator of a DoS attacks 

Vendors have developed modern security technologies to defend against different forms of DoS attacks. You can acquire a DoS protection service that detects and blocks abnormal traffic flows and redirects traffic away from your network. A DoS security solution filters out DoS traffic and allows legitimate requests to pass.

You can also implement a disaster recovery plan to ensure successful mitigation, quick recovery, and efficient communication in the event of a DoS attack.

It is essential to take steps to enhance the security posture of all internet-connected devices to prevent malicious activities. You can install an antivirus program and firewall to restrict incoming and outgoing traffic. You can configure the firewall to block SYN flood attacks. Businesses should train employees to follow acceptable security practices. Organizations can also partner with a managed service provider to enhance security capabilities.