Microsoft stopped the largest DDoS attack on record earlier this year

Microsoft logo at Ignite
Microsoft logo at Ignite (Image credit: Windows Central)

What you need to know

  • Microsoft mitigated a DDoS attack that peaked at a bandwidth of 2.4 Tbps.
  • The attack targeted an unnamed customer in Europe in August 2021.
  • It is the largest DDoS attack on record, surpassing an attack on Amazon that reached a peak of 2.3 Tbps.

Microsoft mitigated the largest Distributed Denial-of-Service (DDoS) attack on record earlier this year. The attack targeted an unnamed Azure customer in Europe and peaked at a bandwidth of 2.4 terabytes per second (Tbps). That attack bandwidth is 140% higher than the previous high mark that Microsoft recorded. Microsoft breaks down the attack and how it protected the targeted company in an Azure blog post. The attack was mitigated by Microsoft in the last week of August 2021.

According to Microsoft, the attack lasted longer than 10 minutes and included short bursts of high traffic. The bursts hit peaks of 2.4 Tbps, 0.55 Tbps, and 1.7 Tbps. Attacks like this aim to overwhelm targets with too much traffic, causing a site or service to go offline.

Source: Microsoft (Image credit: Source: Microsoft)

While the attack's bandwidth of 2.4 Tbps was the largest on record, it fell short of what Azure's DDoS protections could handle. "Azure's DDoS protection platform, built on distributed DDoS detection and mitigation pipelines, can absorb tens of terabits of DDoS attacks," explains Microsoft. "This aggregated distributed mitigation capacity can massively scale to absorb the highest volume of DDoS threats, providing our customers the protection they need."

Microsoft states that the targeted customer did not experience any impact or downtime. An attack of this caliber could cause significant financial damage and other issues if successful.

"The attack traffic originated from approximately 70,000 sources and from multiple countries in the Asia-Pacific region, such as Malaysia, Vietnam, Taiwan, Japan, and China, as well as from the United States," explains Microsoft's Amir Dahan, senior program manager, Azure networking.

The previous largest mitigated DDoS attack reached a peak of 2.3 Tbps and was stopped by Amazon Web Services in June 2020 (via The Verge).

Sean Endicott
News Writer and apps editor

Sean Endicott brings nearly a decade of experience covering Microsoft and Windows news to Windows Central. He joined our team in 2017 as an app reviewer and now heads up our day-to-day news coverage. If you have a news tip or an app to review, hit him up at