Square has stated that there is “no evidence” of a cyberattack contributing to the outage that affected its customers and small businesses. The payment technology company conducted a post-mortem of the daylong outage and concluded that the issue was caused by a DNS problem.

DNS, or domain name system, is a global protocol that translates human-readable web addresses into IP addresses. This enables computers to locate and load websites. However, if a company’s DNS settings are misconfigured or changed incorrectly, it can result in the entire company appearing offline. This is what happened with Square.

The company explained that while making standard changes to its internal network software, a combination of updates hindered proper communication between systems, leading to the disruption. The issue also affected Square’s internal tools for troubleshooting and support, temporarily rendering them unavailable.

DNS issues are relatively common due to the complexity of the protocol. It is often said in cybersecurity circles that if there is an issue, it’s usually DNS or the similarly intricate BGP (Border Gateway Protocol). As DNS relies on distributed servers worldwide, the propagation of new DNS settings can take minutes, hours, or even days.

Square provided limited information on the specifics of the DNS issue. The spokesperson for Square’s parent company declined to comment further on the outage.

While DNS issues are typical, cyberattacks targeting DNS services have occurred in the past. In 2016, a massive botnet attack using the Mirai malware targeted internet giant Dyn, resulting in the offline status of major websites such as Twitter, SoundCloud, and Spotify, who relied on Dyn’s services.

It is worth noting that in 2021, Notion and Akamai also experienced DNS issues, causing their services to go offline temporarily. DNS vulnerabilities highlight the importance of ensuring proper configuration and security measures to prevent disruptions.