June Outlook outages attributed to a DDoS attack, confirms Microsoft

Early in June, Twitter users started complaining about Outlook experiencing downtime. It was later revealed to be a Distributed Denial-of-Service (DDoS) attack, affecting around 18,000 users. The attack was reported by The Associated Press (AP). Microsoft confirmed the attack and provided technical details and recommendations in a blog post on Friday.

According to Cybernews, the attack was initiated by a group known as Anonymous Sudan. The group claimed responsibility for the attack, which lasted approximately 1.5 hours. The impact of the attack is uncertain, as Microsoft has not provided specific details.

Jake Williams, a former offensive hacker with the National Security Agency, commented on the incident, stating that the impact cannot be measured without detailed information from Microsoft. He also noted that this level of attack on Outlook is unprecedented.

In previous years, Microsoft faced major DDoS attacks, with one in 2021 reaching a record-breaking 2.4 terabits per second (Tbps) and another in 2022 peaking at 3.47Tbps. The size of the traffic bursts in the June attack is unknown.

According to Microsoft’s blog post, the DDoS attack targeted OSI layer 7, which is where network applications access services. The attackers, referred to as Storm-1359 by Microsoft, utilized botnets and tools to launch the attack from multiple cloud services and open proxy infrastructures. The motive behind the attack appeared to be disruption and gaining publicity.

We have contacted Microsoft for a comment and will update this article with their response.