What are Zombie systems?

In the Information security realm, there are different types of attacks occurring all over the world. There are virus attacks, phishing, worm attacks, DOS  and DDoS attacks and others. In order to understand “Zombie systems”, we have to talk about DDoS(Distributed Denial of Service) attacks.
What are DDoS attacks?
Imagine a situation, when you are trying to shop on a website – but you are not able to access it. Even after repeated tries, the website is still unreachable. Why do you think this is so? One possible reason may be that the website may be under a DDoS attack.

What are DDoS attacks and what role do Zombie systems play in it – let’s read on…
When a server is inundated with useless requests, it wastes time tending to the countless useless requests and is not able to handle the genuine requests. The attacker controls an innocent computer to make the attack. This computer that is caught in the crossfire between the attacker and the server is the “zombie computer”. When the attacker controls a huge number of zombie computers to make the attack, the zombie computers are known as “Zombie systems”. The zombie systems do not know that they are under the control of the attacker. The attacker can also simultaneously control the zombie systems to launch the attack on the server.
Examples of DDoS attacks:
DDoS attacks unfortunately, are,  very much a reality in today’s world. Let us see a few examples that occurred in 2016 and 2017.
Brian Krebs, the notable investigative reporter from krebsonsecurity.com,was targeted in 2016 and his site was subjected to a large DDoS attack of 620 Gbps(Giga bits of traffic per second!)
Github suffered the largest known DDoS attack on February 28,2018 for close to 10 minutes. The traffic peaked at 1.35 Tbps(Terabits per second) rendering the site unusable then. 
We have seen the meaning of “Zombie systems” in relation to DDoS attacks.
This post is for alphabet ‘Z’ for the Blogchatter challenge… the previous alphabets are here…

1. ‘A’ – Asset
2.     ‘B’ – What is Blockchain ?
3.      ‘C’ – Caesar cipher
4.     ‘D’ –  Detroit
5.     ‘E’ – Empowering women
6.     ‘F’ – Four concepts of Blockchain
7.     ‘G’ – Go green
8.     ‘H’ – Hyperledger Composer
9.     ‘I’ – India
10.     ‘J’ – Java 101
11.     ‘K’ – Kulambu
12.     ‘L’ – List of Information security certifications
13.     ‘M’ – Michigan
14.     ‘N’ – NIST publications
15.     ‘O’ – Object oriented programming
16.     ‘P’ – Palm tree fruit
17.     ‘Q’ – Quiet
18.     ‘R’ – For the love of ‘Reading’….
19.     ‘S’ – Security
20.     ‘T’ – Time
21.      ‘U’ – Usage of Information security
22.      ‘V’ – VPN
23.   ‘W’ – Why do parents name their children after Gods?
24.   ‘X’ – XOR operator in Java
25.   ‘Y’ – Yoga – the panacea for all ills?