Microsoft has confirmed hackers were responsible for a serious outage of Office suite programs this month.
The Outlook email, OneDrive and cloud computing platform were all plagued by sporadic disruptions, for which a shadowy hacktivist group claimed responsibility.
Initially, Microsoft was reticent to confirm the attack, but the company now says a group called Anonymous Sudan is behind the outage.
The group claimed responsibility on its Telegram social media channel at the time.
Some security researchers believe they’re Russian.
In a blog post, Microsoft said the attacks “temporarily impacted availability” of some services.
It said the attackers were focused on “disruption and publicity” and likely used rented cloud infrastructure and virtual private networks to bombard Microsoft servers from so-called botnets of zombie computers around the globe.
Microsoft said there was no evidence any customer data was accessed or compromised.
Cyber security researcher Jake Williams said the scale of damage was not known.
“We really have no way to measure the impact if Microsoft doesn’t provide that info,” he said.
He said Microsoft’s apparent unwillingness to provide an objective measure of customer impact “probably speaks to the magnitude”.
The Microsoft incident highlights how distributed denial of service attacks remain “a significant risk that we all just agree to avoid talking about”, New York University professor Edward Amoroso said.
“It’s not controversial to call this an unsolved problem.”
Serious impacts from the Microsoft 365 office suite interruptions were reported on June 5, peaking at 18,000 outage and problem reports.
On Twitter that day, Microsoft said Outlook, Microsoft Teams, SharePoint Online and OneDrive for Business were affected.
Attacks continued through the week, with Microsoft confirming on June 9 that its Azure cloud computing platform had been affected.
On June 8, the computer security news site BleepingComputer.com reported that cloud-based OneDrive file-hosting was down globally for a time.
Microsoft said at the time that desktop OneDrive clients were not affected, BleepingComputer reported.
