Through various services that block further attacking traffic, companies and organizations can protect themselves against overload attacks.

But it costs money.

Unlike other forms of cyber attacks where the attacker gets into systems and mind or destroys information, an overload attack is not particularly harmful.

- It is accessibility that is under attack.

It is not very important that, for example, SL's website works because the subway can still run, says Pontus Johnson, professor of network and systems engineering at KTH.

Many groups located in Russia

In theory, these types of groups could repeat their attacks over and over again.

- Unless they come up with second thoughts to use their botnet to make money instead, there is no cost to them to continue.

Congestion attacks are easy to perform.

However, getting in and destroying or leaking information is usually more difficult.

In addition, hacker groups are rarely caught.

- Many of these groups are located in countries like Russia and they have no interest in handing over their cyber attackers to other countries.

It could be because they are actually employed by the Russian state or that they are running state affairs, says Pontus Johnson.

Technical debt

All countries are vulnerable to IT attacks, even Sweden.

But there is a big difference between sectors with high IT security such as defense and banks compared to, for example, municipalities where protection is often worse.

- Most systems we depend on have many vulnerabilities and they can be exploited.

You could say we have a technical debt now.

In addition, we put more and more things of value into computer systems.

If you are worried about your IT security as a private person, there are several things you can do.

- You must ensure that your systems are updated so that vulnerabilities are fixed.

You shouldn't have bad passwords and make sure you have backup copies of your important data, says Pontus Johnson.

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Internet expert Måns Jonasson answers three questions about how an overload attack works.

Photo: SVT