Microsoft Corporate E-Mails Tapped by Russian Attackers

Some Microsoft e-mails were exfiltrated by "Midnight Blizzard," a Russia-sponsored attack group, Microsoft announced on Friday.

The attacks, which breached some of Microsoft's corporate e-mail accounts, possibly over a month's period of time, were found to have started in "late November 2023." Microsoft only detected the issue "on January 12, 2024." 

The attackers were looking for Microsoft's knowledge about themselves, apparently, per Microsoft's investigation.

The investigation indicates they [the attackers] were initially targeting email accounts for information related to Midnight Blizzard itself. We are in the process of notifying employees whose email was accessed.

Some senior leadership Microsoft corporate e-mails were accessed, along with any attachments. Microsoft doesn't think that its customer accounts were affected by the attack. It is disclosing information about it as part of its Secure Future Initiative pledge of transparency.

In password spray attacks, commonly used passwords are tried across a network to gain access. In this case, the threat actors managed to gain password access on old nonproduction Microsoft test accounts. From that foothold, the attackers were able to gain permissions and "access a very small percentage of Microsoft corporate email accounts, including members of our senior leadership team and employees in our cybersecurity, legal, and other functions," the announcement indicated.

In reaction to the breach, Microsoft pledged to "act immediately to apply our current security standards to Microsoft-owned legacy systems and internal business processes, even when these changes might cause disruption to existing business processes."

Microsoft is continuing its investigation and declared that it plans to "take additional actions based on the outcomes of this investigation and will continue working with law enforcement and appropriate regulators."

The Midnight Blizzard attack group used to be called "Nobelium" by Microsoft back in 2021 when they had conducted widespread espionage on U.S. government agencies, compromising Exchange Online e-mails through various methods. Microsoft switched to a bad weather naming convention for attack groups last year.

About the Author

Kurt Mackie is senior news producer for 1105 Media's Converge360 group.