Cloud based applications part of Microsoft’s Office 365 went down yesterday. Users of Office 365, Outlook, Exchange, SharePoint, OneDrive, and Azure also reported issues logging in. When a login was attempted, the system returned a “transient error”. The issues began around 5PM EST and did not get resolved for most people until 10PM EST.
With an outage this large, many would be quick to assume this was a cyber-attack. There currently is no evidence to support the claim that this was a cyber-attack. Some reports believe it to be a code issue that caused the outages. The first sign of this outage came from a Microsoft 365 status message on Twitter that indicated Microsoft “identified a recent change that appears to be the cause of the issue”. Microsoft noted they would be rolling back this change to mitigate the impact. However not long after, another tweet was posted that said Microsoft was “not observing an increase in successful connections” from the rollback. It took two hours for services to improve after Microsoft began rerouting traffic to “alternative infrastructure”.
One could also assume this could be the result of a distributed denial of service (DDoS) attack, but that also seems to not be case. According to a statement made by Microsoft, “we've seen no indication that this is the result of malicious activity”. Another Microsoft status update message pointed to “a specific portion of our infrastructure” that failed to process authentication requests.
Services should now be back to normal for all Office 365 applications.
