Humans represent a mystery to be deciphered by security/cybersecurity experts because their behaviors, attitudes, beliefs, rituals and decisions (the general characteristics that define a culture) constitute a little-understood universe for executives and their heads of security. Frequently cited in various international research projects and reports is the fact that people are the weakest links in the security chain. Time and again, it is determined that, despite all the technical efforts and security procedures, people are highly likely to expose organizations to vulnerabilities.
source:
The Human Factor in Information Security (isaca.org)
“Chain” is defined here as the sequence of connected links that enables a system to function. Its strength is defined in terms of the connection that is least strong.
Dreyer, P.; T. Jones; K. Klima; J. Oberholtzer; A. Strong; J. Welburn; Z. Winkelman; “Estimating the Global Cost of Cyber Risk: Methodology and Examples,” Rand Corporation, 2018, https://www.rand.org/pubs/research_reports/RR2299.html