Internet outage in South Korea over a large DDoS attack

A major South Korean telecom operator, KT Corp., was hit by a distributed-denial-of-service (DDoS) attack, leaving millions offline on Monday.

Several hours later, the company announced that the reason behind the outage was not a DDoS attack, but a 'routing error.'

"We initially assumed it was a DDoS (attack) due to traffic overload, but after close analysis, we determined the cause as a routing error," KT said in a statement.

Networks disruptions took effect nationwide, with KT Corp’s customers unable to access the internet for around 40 minutes, local media reports.

At first, the company identified a DDoS attack behind the disruption, although KT Corp. revealed neither the culprit nor the intensity of the attack. KT Corp. restored services to most users after around 40 minutes.

The effects of the attack were felt around 11 AM, with payment, wireless and wired internet, and call services going dark all over the country. Reuters reports South Korean police are starting an investigation over the cyber attack.

On the rise

DDoS attacks came back into the spotlight recently with the emersion of the Mēris botnet, considered one of the largest in history. Mēris botnet hit a Russian tech giant Yandex with the largest DDoS attack in history. The record-breaking attack, however, was likely just a test drive.

Recent reports show that 2021 will be yet another record year for the number of DDoS attacks carried out. Threat actors launched approximately 2.9 million DDoS attacks in the first quarter of 2021, a 31% increase from the same time in 2020.

During DDoS attacks, vast numbers of “bots” attack target computers. Hence, many entities are attacking a target, which explains the “distributed” part. The bots are infected computers spread across multiple locations. There isn’t a single host. You may be hosting a bot right now and not even know it.

When DDoS attackers direct their bots against a specific target, it has some pretty unpleasant effects. Most importantly, a DDoS attack aims to trigger a “denial of service” response for people using the target system. This takes the target network offline.

If you’ve repeatedly struggled to access a retail website, you may well have encountered a denial of service. And it can take hours or days to recover from.