On Friday night, the food chain Coop's checkout system crashed - and most of the stores were kept closed on Saturday.

Apotek Hjärtat, the train company SJ and the petrol chain St1 have also experienced disruptions.

The reason for the crash is an IT attack on the American software company Kaseya, whose software the mentioned companies use.

Pressed on money

It is not only in Sweden that companies have been affected.

According to the news site Bloomberg, which refers to the IT security companies Huntress Labs and Eset, more than 1,000 companies in eleven countries have been affected.

The purpose of the attack is, according to several IT security experts, to try to pressure companies on money.

According to John Hammond at Huntress Labs, several of the affected companies have now been required to pay anything from tens of thousands of kronor to tens of millions of kronor in ransoms, reports the NY Times.

"Completely exploded"

Coop's press service confirms that their disruption is related to the IT attack on Kaseya, but they do not want to comment on whether they have been pressured for money.

Mikael Westerlund, technical manager at the data provider Globalconnect, says that similar attacks have become increasingly common.

- This is about financial crime.

It has completely exploded in the last three years and it is clear that it has become a business, he says to SVT.

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See how the IT attack affects the country's Coop stores.

Photo: Daniel Brodén / SVT