Microsoft said on Friday that the outages that affected certain services of the company through some of the earlier days of this month were the result of cyberattacks, but said it saw no evidence of any customer data being accessed or compromised.

“Beginning in early June 2023, Microsoft identified surges in traffic against some services that temporarily impacted availability'” the company said in a blog post.

Microsoft said it opened an investigation and began tracking the DDoS activity by the threat actor it refers to as Storm-1359 after it identified the threat.

Microsoft did not immediately respond to a request by Reuters as to whether the company had identified the party responsible for the attack.

DDoS attacks work by directing high volumes of internet traffic towards targeted servers in a relatively unsophisticated bid to knock them offline.

Microsoft’s 365 software suite, including Teams and Outlook, were down for more than two hours for over thousands of users on June 5 and a brief recurrence the following morning. That was the fourth such outage for Microsoft in a year.