The first step to mitigate further risks when a systems audit uncovers a shared drive folder containing sensitive employee data with no access controls is to restrict access to the folder. This can be done by implementing appropriate access controls, such as user authentication, role-based access, and permissions, to ensure that only authorized individuals can view and access the sensitive data.
Reference:
https://www.sans.org/cyber-security-summit/archives/file/summit-archive-1492158151.pdf
https://www.itgovernance.co.uk/blog/5-reasons-why-employees-dont-report-data-breaches/
https://www.ncsc.gov.uk/guidance/report-cyber-incident