Breaches occur because vulnerabilities are exploited. It does not mean attackers used complex, undetectable zero-day exploits to compromise a system and exfiltrate data. It does mean that a weakness existed, an attacker took advantage of it, and the activities went undetected. A successful breach against an organization also does not always mean incompetence or negligence was the root cause. Sometimes organizations with mature processes and talented staff suffer breaches. Sometimes there are just too many variables and too much noise.
Security operations ...