ZDNet was able to acquire a copy of the alert sent out by the Secret Service which included best practices for MSPs, those include:

• Have a well-defined service level agreement
• Ensure remote administration tools are patched and up to date
• Enforce least privilege for access to resources
• Have well-defined security controls that comply with end-user regulatory compliance
• Perform annual data audits
• Consider local, state, and federal data compliance standards
• Proactively conduct cyber training and education programs for employees

The best practices for MSPs customers are as follows:

• Audit Service Level Agreements
• Audit remote administration tools being utilized in your environment
• Enforce two-factor authentication for all remote logins
• Restrict administrative access during remote logins
• Enforce least privilege for access to resources
• Utilize a secure network and system infrastructure, capable of meeting current security requirements
• Proactively conduct cyber training and education programs for employees

Proactive monitoring of workstations and servers at both the MSP and client systems is the best way to detect attacks and prevent serious damage from resulting. A Security Operations Center (SOC) operating 24 hours a day can respond to mitigate threats quickly, as long as the security analysts have visibility into events that happen on the network and endpoints.

Sources: https://www.zdnet.com/article/us-secret-service-reports-an-increase-in-hacked-managed-service-providers-msps/