This is The Guardian.

In December of 2020, the IT manager for a school in Central London received a text message from a colleague, saying the school's website was down.

He tried logging on, but couldn't. At first he thought he had forgotten the password. After several attempts, he realised that he was locked out.

The IT manager, Matthew, he asked us not to use his last name. Works in a central London neighbourhood where affluence hides pockets of poverty, and migrant families from Pakistan, India and Eastern Europe pin their hopes for their children on a small, publicly funded school.

It has about 150 students aged between 5 and 10, many of them on free school meals. On a shoestring budget, in a Victorian building that's showing its age, teachers track the students' progress by photographing them as they learn how to hold a pencil.

Draw a picture, or write their name.

The snapshots and other progress reports are uploaded to a server, a powerful computer that processes data and provides services for other devices used around the school.

An affable Englishman in his early 40s with blonde hair and a stubble beard, Matthew has guarded this irreplaceable trove of data on every child's learning since 2016.

Although the school can only afford to pay him a few thousand pounds a year as a contractor, he is devoted to its people and mission. When he found he couldn't access the website, he was desperate.

At 2am, having exhausted other ideas, he finally contacted the help desk of the company that hosted the server. He obtained a new server and connected it to the school.

With the fresh setup, Matthew could see the files listed in the directories, though he still couldn't open them. They had been renamed with the file extension dot encrypt.

To his horror, he realised that the school had been hit by a ransomware attack. One of the world's most pervasive and fast-disgrowing cybercrimes.

Across between hacking and cryptography, ransomware penetrates computers and renders files inaccessible without the right decryption key.

The hackers then demand a hefty price for the string of characters that can unlock the information.

The hacker had entered the school system through a web portal that teachers used for content management.

An update with improved security was available, but Matthew, who manages IT for a variety of clients and is so busy that he doesn't always remember to patch vulnerable software, hadn't installed it.

I didn't follow my own advice. I was so frustrated and so embarrassed, he said. I felt like someone punched me in the stomach.

As George Allwell once observed, the history of civilization is largely the history of weapons.

Today, digital weapons are reshaping the world, and ransomware poses what may be the greatest threat of all.

It's more efficient and profitable than other cybercrimes such as identity theft.

And as we become dependent on the internet for every aspect of our lives, there is an almost limitless possibility for criminals to make money and create mayhem.

The frequency and the impact of ransomware attacks are widely understated, because many victims don't make them public or inform the authorities.

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