Russian state-sponsored threat actors attacked Microsoft late last year and managed to steal confidential information from certain high-ranking people, including top executives, the company confirmed.
It is not known exactly how many emails were accessed, but Microsoft said the compromised accounts included those belonging to senior leadership members and those working in the legal and cybersecurity departments.
The attack was detected on January 12, and Microsoft noted that subsequent changes to the security approach could cause some disruptions.
Steal confidential data
In a blog post, the company noted how a group known as Nobelium (aka Midnight Blizzard) managed to compromise a legacy, non-production test tenant account via a password spray attack, in late November 2023. .
The group used that access to gain access to “a very small percentage” of Microsoft corporate accounts, the company said.
“Some emails and attached documents” were stolen, the announcement reads, specifying that the information was related to the Nobelium group. “To date, there is no evidence that the threat actor had access to customer environments, production systems, source code, or artificial intelligence systems.”
The investigation is still ongoing, and if Microsoft discovers that customer data was stolen, it will notify affected individuals. At this time, there is nothing customers can or should do.
Going forward, the company will also apply its current security standards to legacy systems and internal business processes, “even when these changes may cause disruptions to existing business processes.” While this will likely cause some level of disruption, Microsoft sees it as a necessary first step in protecting its infrastructure. At the same time, the investigation will continue as the police and other relevant authorities are being notified.
We last heard from Nobelium in March 2023, when the group breached 40 companies via compromised Microsoft 365 accounts, but it is perhaps best known for its cyberattacks against SolarWinds in 2019 and the Democratic National Committee in 2015.
