A chilling near-miss shows how today’s digital infrastructure is vulnerable

FeW INVENTIONS in history have been as important for human civilisation and as poorly understood as the internet. It developed not as a centrally planned system, but as a patchwork of devices and networks connected by makeshift interfaces. Decentralisation makes it possible to run such a complex system. But every so often comes a chilling reminder that the whole edifice is uncomfortably precarious.

On March 29th a lone security researcher announced that he had discovered, largely by chance, a secret backdoor in XZ Utils. This obscure but vital piece of software is incorporated into the Linux operating systems that control the world’s internet servers. Had the backdoor not been spotted in time, everything from critical national infrastructure to the website hosting your cat pictures would have been vulnerable.