Microsoft Azure Attack Shows Persistence of Blunt Hacking Tool

The recent outage on Microsoft Corp.’s cloud-computer platform demonstrated the persistence of an older, blunt-force style of cyberattack.

It’s called a distributed denial-of-service attack, DDoS for short, and it works by directing massive amounts of junk internet traffic at a target, like a website or server, to disrupt it or even knock it offline. It’s become a favorite tool of hacktivists seeking to make a statement by targeting government institutions, banks or major companies.

The attack on Microsoft started Tuesday morning, hours before the technology giant was scheduled to announce quarterly earnings. Customers of its Azure cloud platform faced ...