PowerShell Threats Grow Further and Operate in Plain Sight — Symantec

https://www.symantec.com/blogs/threat-intelligence/powershell-threats-grow-further-and-operate-plain-sight

Malicious PowerShell attacks increased by 661 percent from the last half of 2017 to the first half of 2018, and doubled from the first quarter to the second of 2018.

There are some good guides from the major security vendors on the risks of PowerShell exploitation. No solution is complete, but some sensible steps can be taken.