Which 2016 cyberattack caused major internet outages by using hacked IoT devices?

The 2016 cyberattack that caused major internet outages by using hacked IoT devices was the Mirai botnet attack.

Mirai scanned the internet for connected cameras, digital video recorders, and other devices protected by factory-set or weak credentials. After infecting them, it organized them into a botnet that could send enormous distributed denial-of-service traffic. On 21 October 2016, a Mirai-based attack against DNS provider Dyn disrupted access to many prominent websites.

The outage affected services including Twitter, Reddit, Netflix, and GitHub in parts of the United States and Europe. The incident showed that consumer devices with modest computing power could become powerful when controlled in large numbers.

Mirai’s source code was later released publicly, leading to many variants. The core lesson was not limited to one brand or device type: changing default passwords, updating firmware, disabling unnecessary internet exposure, and segmenting networks all reduce IoT botnet risk.