Cuba uses critical vulnerability to hack server Microsoft Exchange

Microsoft reports that the group

The group purposefully attacks a wide range of organizations and personalities, including government agencies, critical infrastructure suppliers and private companies in the field of finance, health and telecommunications. The group is especially interested in stolen confidential information, such as credit and banking data, trade secrets and political information. In this regard, there is an opinion that they are a state group that uses information to achieve its political goals. However, officially no one recognized responsibility for the actions of this group.

/Media reports cited above.