Fundamental questions, like how the SolarWinds hackers got into its systems from the start, still aren't answered.

The lawmakers have questions about what they're trying to do to fight it, and more.

The company operates in cyberspace in much the same fashion that nation-states do.

The attackers “apparently deem[ed] the powerful SolarWinds backdoor too valuable to lose in case of discovery,” Microsoft said.

The illicit access would have allowed attackers to spy on Mimecast clients.

The company said it saw no indications that its systems were used to attack others.