Microsoft said on Friday that the Russian state-backed hacking group Midnight Blizzard is trying to breach its systems again using information it stole by hacking into the tech giant’s corporate emails in January.
In the January attack, a hacking group also known as Nobelium breached Microsoft’s corporate email systems and stole emails and documents from employee accounts.
“In recent weeks, we have seen evidence that Midnight Blizzard is using information originally exfiltrated from our corporate email systems to gain or attempt to gain unauthorized access,” the company said in a statement on its blog.
That data includes some source code repositories and internal systems, Microsoft said.
The company’s shares fell slightly after the news,
“Obviously, Midnight Blizzard is trying to use the secrets of the different types it found,” he added. “Some of these secrets were shared between customers and Microsoft in email, and as we discover in our exfiltrated email, we have and are reaching out to those customers to help them take mitigation measures.”
In some ways, hackers have become more aggressive in trying to break into Microsoft, the company said. For example, the hacker’s use of “password injection” — where an attacker uses the same password on multiple accounts in the hope of gaining access to them — has increased up to tenfold compared to their January attack, Microsoft said.
The Russian Embassy in Washington previously did not respond to requests for comment on Microsoft’s statements about the Midnight Blizzard attack.
Microsoft added that it had no evidence that its customer systems were compromised in the hack.
