A leading global bank faced a devastating ransomware attack that exploited vulnerable APIs and weak VPN encryption. Hackers not only locked critical systems but also harvested RSA-encrypted customer data – including account details and transaction records – for future quantum decryption. The immediate damage totaled $20M ($2M recovery, $5M downtime, $3M GDPR fines, $10M customer churn), with a looming $50M quantum fraud risk if stolen data was later decrypted. The breach escalated into a national security concern, threatening financial system stability.