Denial-of-Service attack is a security event that occurs when an attacker takes action that prevents legitimate users from accessing the target computer, device, website, or other network resource. Denial-of-Service can cause damage to many businesses and does so every day around the world. This attack is not only harmful to the businesses, but it can be a major inconvenience to the every day user trying to access websites. Even with our modern day technology and security, we are still just as likely to get hit with theses attacks as businesses were years ago when the Internet was still growing.

How it Happens

Denial-of-service is typically accomplished by flooding the targeted machine or resource, such as Facebook's servers. With requests in attempt to overload the system and prevent users from accessing the website. An easy way to think about how this works is when you are driving on the interstate to work and it seems that traffic is normal everyone is going 65MPH and it is slightly relaxing. You are about to get to your destination which is exit B2 Facebook ST, and suddenly, there is a huge line of care at that exit so big that you can see the cars all the way to the Facebook building connecting to the interstate. You stay frustrated and annoyed because you need to get to work but there is nothing you as the user can really do about it.

  • This is a real-world example of how Denial-of-service happens because this has

happened to me many times when trying to get downtown during rush hour.

Example and Explanation


[img] This is a straightforward and starts with the user declaring two variables. A and B. Both A and B have sizes of 50 and 16. The program will ask the user for the name and it uses the "gets" function in order to receive the input. The data that the user inputs is copied from A to the buffer variable and then the function is complete. In this situation, the issue is with the "gets" function. This function by itself does not have any form of bound checking. So "gets" will not actually check if what the user entered is actually 50 characters or less. This means that if the user uses more then 50 characters the program will crash.

To put it in a real world example: if this code was used as a sign up for a newsletter and someone entered 51 characters in the name box, the program would crash and could cause the website you are signing up for to be down. This same user could keep doing this over and over again until the owners of the website fix the code so that this does not happen.

Why is it dangerous?

  1. Users hate having to wait for websites to open up.
  2. The website can lose customers as a result, which will hurt the company in return.
  3. The workers at the company being attacked will not be able to work since their services are down.
  4. When your workers are not able to work you either have to send them home or keep them on the clock not making the company any money.
  5. The cost that companies will easily incurr is more than $50k in recovery bill from a DOS attack. [Cost]

Why does it happen?

I actually have a theory on this. When it comes to attacks on a major network such as anything to do with credit cards like Shazam or social media like Facebook.

  • Shazam will be attacked because it will make it harder for people to use their ATMs which in return will make Shazam lose money. This opens a window of opportunity for the attackers to request money from Shazam to stop the attack.
  • Facebook will be attacked because of similar reason, but I personally think the attack is coming mostly from another company. Not necessarily the company attacking but one employee that thinks he is doing the right thing. A few years ago when I was playing a game called Guild Wars 2 they released new content and right after the release they were hit with a DOS attack making it impossible for players to log in and play the game. There is no reason to attack a company for a video game unless you are trying to get players to play a different game. [Why]

Different Types of Attacks

Distributed DOS

  • DDoS is a type of DOS attack where multiple compromised systems, which are often infected with a Trojan, are used to target a single system causing a Denial of Service (DoS) attack. Victims of a DDoS attack consist of both the end targeted system and all systems maliciously used and controlled by the hacker in the distributed attack. [DoS]_

Advanced Persistent DOS

  • These attacks are caused by more skilled hackers. The attacks involve multiple layers of attacks, starting with application layer floods, followed by repeated SQLI and XSS attacks. [DoS]

How to protect myself

Typical users do not need to worry about being the target of a denial of service
attack. There are a few exceptions to this though listed below.
  1. Online streamers
  2. Professional gamers
  3. Social Media Influencer
  4. YouTube Stars
It is uncommon for one specific user to be the target of an attack. [geek]
The tricky thing here is that there is no real way to prevent a DoS attack. It is almost impossible to tell the difference between a normal request and a malicious request, because they come to the endpoint the same way. There are a few things you can do to help prevent and make it not as effective.
  1. Have PLENTY of bandwidth. Although this can rack up a big bill, it is easier to keep your services up and running if you have free bandwidth.
  2. DoS attack identification. This helps with trying to decide if the request is real or malicious. This is not the perfect system but it can help.
  3. Prepare for DoS response. Using technology to slow down people connections or limiting each request to half a megabyte for example can prevent the attack from taking over and shutting down the service.
All in all, there is not perfect way to prevent the attack. To me, it works like

cold and flu medicine; it's great stuff and helps, but you can still catch a cold



[Cost]Barker, Ian. "DDoS Attacks Are More Dangerous than You Think." BetaNews. BetaNews, 18 Sept. 2015. Web. 23 Feb. 2017. <>.
[Why]Zeltser, Lenny. "9 Reasons for Denial-Of-Service (DoS) Attacks: Why Do They Happen?" Lenny Zeltser Content. Zeltser Security Corp, 26 Aug. 2016. Web. 27 Feb. 2017. <>.
[Dos]"Denial-of-service Attack." Wikipedia. Wikimedia Foundation, 26 Feb. 2017. Web. 27 Feb. 2017. <>.
[geek]Stewart, Dennis. "What Are Denial of Service and DDoS Attacks?" HowTo Geek RSS. How-To Geek, 28 Nov. 2016. Web. 27 Feb. 2017. <>.
[safe]Chapple, Mike. "How to Prevent DoS Attacks in the Enterprise." SearchSecurity. Tech Target, n.d. Web. 27 Feb. 2017. <>
[img]Sanders, Chris. "Buffer Overflows, Data Execution Prevention, and You." TechGenix. TechGenix, 28 Oct. 2009. Web. 27 Feb. 2017. <>.

Written by Rasim, Edited by Kyann and Kyle.