KT Corporation reports a nationwide service outage, suspects routing error as the cause

KT Corporation Service Outage Routing Error Misconfiguration Border Gateway Protocol BGP Downtime

South Korea’s second-largest telecommunication firm, KT Corporation, reported experiencing a nationwide service outage that left more than 16.5 million Korean customers disconnected from the internet and phone services for less than an hour.

Because of the outage, schools were affected, including students that attend online classes. Health staff were unable to access patient data, and credit card processing in stores was disrupted. Food delivery orders were also delayed. 

Seoul’s cybersecurity department team has assisted KT Corp. in investigating and solving the outage problem.  


KT Corporation first suspected a distributed denial-of-service (DDoS) attack had caused the outage. However, they have eventually found out that a routing error in its system was the real cause of their service’s downtime issue. 


Security researchers stressed that faulty routing configurations are disastrous for organisations. They added that KT Corp’s incident could be similar to the Border Gateway Protocol (BGP) routing issue that recently shut down popular social media platforms Facebook, Instagram, and WhatsApp. 

The telco firm has immediately solved the outage incident within 40 minutes. However, they did not provide any reason that caused the downtime of their services, adding that the issue is still under the security team’s investigation. 

For now, it is presumed that a BGP misconfiguration was the root of the outage. The telco firm told the media that it is working with its risk management committee to recover from the problem quickly. Data packets are prevented from accessing their intended IP addresses and servers during a BGP routing error, causing a wide service disruption. 

Two other major telco firms in Korea, LG Uplus and SK Telecom, suddenly reported an overload to their services due to the outage of KT Corp. Customers may have relied on these two telco firms as an alternative to being connected online while the outage issues on KT Corp. is being handled. Though the incident has brought confusion to the industry, the IT Ministry has clarified that none of the mentioned telco firms is experiencing a DDoS attack. 

In 2018, KT Corporation suffered a major outage as a fire broke on one of its branches. The telco firm was forced to reimburse its customers’ service subscriptions. Services have been greatly disrupted during that time that took days before being fixed. 

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