Microsoft says Kremlin-backed hackers accessed its source and internal systems

In the months since, Microsoft said Friday, Midnight Blizzard has been exploiting the information it obtained earlier in follow-on attacks that have stepped up an already high rate of password spraying.

Unprecedented global threat

Microsoft officials wrote:

It is apparent that Midnight Blizzard is attempting to use secrets of different types it has found. Some of these secrets were shared between customers and Microsoft in email, and as we discover them in our exfiltrated email, we have been and are reaching out to these customers to assist them in taking mitigating measures. Midnight Blizzard has increased the volume of some aspects of the attack, such as password sprays, by as much as 10-fold in February, compared to the already large volume we saw in January 2024.

Midnight Blizzard’s ongoing attack is characterized by a sustained, significant commitment of the threat actor’s resources, coordination, and focus. It may be using the information it has obtained to accumulate a picture of areas to attack and enhance its ability to do so. This reflects what has become more broadly an unprecedented global threat landscape, especially in terms of sophisticated nation-state attacks.

The attack began in November and wasn’t detected until January. Microsoft said then that the breach allowed Midnight Blizzard to monitor the email accounts of senior executives and security personnel, raising the possibility that the group was able to read sensitive communications for as long as three months. Microsoft said one motivation for the attack was for Midnight Blizzard to learn what the company knew about the threat group. Microsoft said at the time and reiterated again Friday that it had no evidence the hackers gained access to customer-facing systems.

Midnight Blizzard is among the most prolific APTs, short for advanced persistent threats, the term used for skilled, well-funded hacking groups that are mostly backed by nation-states. The group was behind the SolarWinds supply-chain attack that led to the hacking of the US Departments of Energy, Commerce, Treasury, and Homeland Security and about 100 private-sector companies.

Last week, the UK National Cyber Security Centre (NCSC) and international partners warned that in recent months, the threat group has expanded its activity to target aviation, education, law enforcement, local and state councils, government financial departments, and military organizations.