Another outage at a major cloud service, what makes them so vulnerable?

Due to a problem with Microsoft's Azure cloud service, the NS (Dutch Railways) app was down yesterday, and passengers were unable to buy train tickets or rent an OV-fiets (public transport bicycle). But it wasn't just NS that was affected: Microsoft Teams, Minecraft, and other websites and apps were also down.

This is the second major internet outage this month, after Amazon's (AWS) web services were also partially disrupted by an outage. That outage took down numerous apps, including social media platforms like Reddit and Snapchat, games like Roblox and Fortnite, and other services including Zoom, Signal, and Duolingo.

In both cases, it was a small mistake with major consequences. The importance of cloud services like Azure and AWS cannot be overstated: these services form the backbone of the modern internet. It's estimated that half of the entire internet runs on Amazon (30 percent) and Microsoft (20 percent) servers. Google also holds a share, with 13 percent.

Major outages are rare, but they do have a significant impact because so many different companies use these types of cloud services. Last year, a major outage occurred at cybersecurity firm CrowdStrike, which shut down airports, banks, and hospitals worldwide.

A contributing factor to the vulnerability of cloud services is that they are sometimes built like a house of cards. Amazon's web services themselves also use each other. When a database service became unavailable this month, it caused a domino effect, causing the company's other services to fail one by one.

On the other hand, cloud services are distributed across many different data centers worldwide, meaning most outages are limited to a single region.

Cloud services make it much easier for companies to build websites or apps. Where they used to have to buy their own servers and hire people to manage them, a cloud service can do it all in just a few minutes.

Using the cloud is also much cheaper than doing it yourself. For a small app or website, it's a matter of euros per month. And the cloud easily grows with a company: even a giant like Netflix runs on Amazon's cloud services. They do, however, spend considerably more on it: an estimated $1 billion per year.

There are also disadvantages to the cloud: besides the vulnerability in the event of major outages, it is also questionable how desirable it is to store sensitive data on the servers of large American companies, to which the American government can also gain access.

The cloud continues to grow rapidly: both Microsoft and Google showed huge increases in cloud service revenue in their quarterly figures today. Amazon, too, has made its cloud division its primary source of revenue, generating greater profits than its online store, for which it is known.

Last month, a Dutch hacker discovered a crucial security flaw in Microsoft's cloud services. This video shows the consequences: