GoalDescribe a DDoS attack and a botnet and say what they do to a website.
New words
DDoS attack · so many requests at one moment that a website cannot serve real visitorsserver · the computer that keeps a website and answers visitorsrequest · a message from a device that asks a server for a pagebotnet · a group of devices secretly controlled by an attacker
Explanation
Picture a shop that is open for customers. Suddenly, thousands of people who do not want to buy anything crowd in and block the door. The real customers cannot enter. This is how a DDoS attack, a distributed denial of service attack, works. A server answers requests from visitors. In a DDoS attack, so many requests arrive at the same moment that the server is slowed down or stopped. The aim is to make the service unavailable, not to steal data. The requests come from many devices that an attacker controls without the owners knowing. This group of devices is called a botnet. It is not the same as the robots in Week 1: a botnet is only a group of controlled devices, with no arms and no wheels. When a school website is hit, students cannot find the timetable.
many controlled devices→thousands of requests at once→one server is overloaded→real visitors are blocked
Worked examples
A street has room for twenty cars an hour. If two hundred empty cars park in it, no real car can pass. The cars are like the requests and the street is like the server. The cars are empty because the aim is to block the street, not to steal.
Who is affected
How
the shop
loses sales and trust
the visitors
cannot open the site
A small shop sells school bags on its website. During a DDoS attack, customers see an error page for two hours. The shop loses sales and customers lose time. Nothing was stolen, but the shop’s service stopped.
Class activity
Draw the DDoS flow as a picture: a row of small devices on the left, an arrow, one big server on the right with a “busy” sign, and a real visitor outside with a question mark. Label the botnet. Add one line: what the attack wants, and what it does not want.
Practice
1
What does DDoS stand for in your own words?
Many devices send so many requests that a service stops working for real users.
2
Is the aim of a DDoS attack to steal data?
No. The aim is to make the service unavailable.
3
What is a botnet?
A group of devices controlled by an attacker, not the robots of Week 1.
4
Name one effect of a DDoS attack on a shop.
The shop loses sales, or customers cannot open the site.
