Microsoft has warned that cyber attackers could target computer networks in a way that could disrupt operations. In a security advisory, the company said that it had observed a “significant” increase in the activities of a cyber espionage group known as Strontium.

The group, also known as Fancy Bear or APT28, is believed to have links to the Russian government. Microsoft said that it had observed Strontium targeting organizations in the energy, nuclear, aerospace, and defense sectors.

The company said that the attacks could involve the use of fake Microsoft Outlook Web Access (OWA) pages to gain access to user …