In December 2016, Yahoo disclosed that a 2013 hack had compromised more than 1 billion accounts. The longer it takes an organization to discover a breach, the more time an attacker has to find and exfiltrate the organizations sensitive data. A majority of data breach victims either dont have adequate systems or managed security services that would help them self-detect data breaches. AT&T surveyed global executives for its Cybersecurity Insights report about breach notifications. The answer is to put into practice a honed, nimble incident response plan.”]
Source: https://www.csoonline.com/article/3159738/how-data-breaches-are-discovered.html