Of the many great things that NERC does for the Electric Industry, one item in particular I find to be extremely useful is the Lessons Learned publications. NERC published the Lessons Learned report from CIP Audits conducted in 2020 and it contains some recommendations that are intended to improve security across the BES. Here are a few of those NERC recommendations:

• Staff observed some entities made security patch implementation decisions based on the risk of exploitation of the vulnerability. The risk of exploitation of a vulnerability is not a  factor in determining the application of a security patch. All identified security patches must be evaluated and then either applied or mitigated.
• If security patches are not accounted for through mitigation plans, security vulnerabilities could be exploited in a malicious manner to gain control of a BES Cyber Asset or BES Cyber System or render the BES Cyber Asset or BES Cyber System inoperable
• entities lacked adequate controls to ensure that all security patches were installed. Staff observed that these issues occurred where entities employed manual tracking processes that were labor-intensive and presented a higher risk of human error. To improve patch management processes, entities should consider additional controls, such as automated methods where possible, and enhanced quality assurance methods where manual methods are still used.
• Entities should consider incorporating the following elements into an entity’s vulnerability assessment process for all Cyber Assets: network port and service identification, network discovery and wireless review,as set forth in NERC CIP-010-2 Guidelines and Technical Basis.Entities should consider incorporating the following elements into an entity’s vulnerability assessment process for all Cyber Assets: network port and service identification, network discovery and wireless review,as set forth in NERC CIP-010-2 Guidelines and Technical Basis. 
• Entities should perform due diligence to ensure that the selected third-party vendors use sufficient security controls. Though not required by the CIP Reliability Standards, entities should consider guidance from NIST SP 800-35 “Guide to Information Technology Security Services,” which recommends that the customer take responsibility for identifying and implementing all security controls required to protect data both in transit and at rest when employing third-party contractors.

I highly recommend a read through the latest NERC CIP 2020 Lessons Learned publication