ABC Corp experienced a major security breach when an employee inserted an infected USB drive found in the parking lot. This introduced malware that spread throughout ABC's systems and gathered credit card information from 20 million customers over three months. The summary identifies failures in ABC's security policies, design, and controls that allowed this breach to occur, such as lack of awareness training, outdated antivirus software, and failure to properly secure administrative access. It provides both short-term tactical solutions like incident response procedures and long-term strategic solutions such as continuous monitoring, user access controls, and moving to behavioral-based security analytics to prevent future attacks.