Major Cybersecurity Incidents and Costs

Cybersecurity breaches can incur massive financial losses and expose billions of records, highlighting the critical need for robust security practices in the tech industry.

The top 3

  1. Top 3 Largest Data Breaches by Records Exposed: The largest data breaches by records exposed include the Chinese Surveillance Network breach (4 billion records in June 2025), the 2013 Yahoo data breach (3 billion records), and the National Public Data breach (2.9 billion records).
  2. Top 3 Costliest Cyberattacks by Financial Impact: The NotPetya/ExPetr malware campaign in 2017 is the most expensive cyberattack to date, costing an estimated $10 billion, followed by the Change Healthcare ransomware attack ($2.87 billion) and the Equifax data breach (over $1.4 billion).
  3. Top 3 Largest Ransomware Payouts: The largest confirmed ransomware payout was $75 million to the Dark Angels gang in early 2024, followed by CNA Financial's $40 million payment in 2021, and CDK Global's $25 million payment in 2024.

Open the full topic