What is the most important criterion when reviewing information security controls?

The most important criterion when reviewing information security controls is to ensure that the controls are effectively addressing risk. This focus on risk management is essential because the primary purpose of implementing security controls is to mitigate the risks associated with information assets. If controls are not effectively managing those risks, then they do not serve their intended purpose, which ultimately puts the organization's information and systems at greater risk of threats and vulnerabilities.

By concentrating on whether controls are effectively addressing risk, organizations can assess their current security posture, identify gaps, and make informed decisions about necessary improvements or changes. This aligns with the risk management framework, which is fundamental to developing and maintaining robust information security strategies.

Reviewing the impact of controls on business operations, providing assurance to management, or establishing baselines are also important factors, but they are secondary to ensuring that the risk is being effectively managed. Without this foundational focus on risk, the other aspects may not lead to meaningful improvements in the organization's security posture.