Denial of Service (DoS)

What is Denial of Service? If you’re thinking of the operating system from the 70’s, good guess, but no! DoS, or Denial-of-Service, is a cyber-attack against IT systems and services like computers or networks.

The attacker searches for a vulnerability they can exploit to make a machine or network resource incredibly slow, or in the worst case, totally unavailable. Typically, this involves generating numerous unwanted requests and forwarding them to the targeted machine. Successful spamming overloads the system, and this causes the system’s actual requests to get stuck in the queue, with the possibility of them getting lost entirely.

Two types of DoS attacks

The main goal of a DoS attack is to make the target unavailable, but there are many different ways to carry out an attack.

Flood attacks

Servers are the typical targets of flood attacks. A malicious hacker is able to oversaturate server capacity by flooding it with a huge amount of requests and packets. The server might then behave differently and produce fewer, perhaps even zero, responses.

Buffer overflow attacks

Buffer overflow attacks aim at the hardware and physical resources. The attack provokes the targeted machine and consumes all of its available resources, such as memory or CPU. This type of attack can cause sluggish behaviour, slower response time from the hardware, or complete system crashes.

What is a DDoS and how is it different from DoS?

  • DDoS, or Distributed Denial-of-Service, is another well-known attack, though in actuality, it is essentially the same thing as DoS. The difference is in the numbers. DoS uses a single connection, while a DDoS attack utilizes many sources of attack traffic. In most cases, DDoS is a coordinated attack of bots. As it was mentioned, the attacks are similar, so extending the source of the malicious traffic is easy to execute.

How do you know if you’re the target of a DoS attack?

denial of service avatao

It is hard to recognize the signs of a DoS attack because the symptoms are similar to common hardware issues, or people may think the net service provider is undergoing maintenance. Nevertheless, the following symptoms could indicate a DoS or DDoS attack:

  • Unexpectedly slow network performance. Much longer webpage loading times
  • No access to a particular website

  • No access to any website
  • Multiple devices on the same network lost their network connection at the same time

Monitoring and analyzing are the best methods to detect an attack, usually via firewall or intrusion detection system.

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