In May 2017, a ransomware attack known as WannaCry spread across the globe, crippling businesses, hospitals, and government systems. It remains one of the most infamous cyber incidents of the decade, and the lessons it taught are still highly relevant today.
What Happened
WannaCry was a type of ransomware that encrypted files on infected computers and demanded payment in Bitcoin to restore access. Within hours, it spread rapidly to hundreds of thousands of machines in more than 150 countries. The attack exploited a vulnerability in Microsoft Windows known as EternalBlue, which had been previously leaked from a set of hacking tools used by a government agency.
Impact of the Attack
The attack caused massive disruption worldwide.
- Hospitals in the UK’s National Health Service had to cancel appointments and surgeries.
- Global companies, including shipping, logistics, and telecom providers, suffered downtime.
- Financial losses were estimated in the billions of dollars.
WannaCry highlighted how a single unpatched vulnerability could disrupt critical services across multiple industries.
Key Lessons Learned
Patch Management Matters
The vulnerability exploited by WannaCry had already been patched by Microsoft before the attack. Organizations that delayed or ignored updates were the most severely affected.
Backups Are Critical
Victims who lacked reliable backups had no option but to either pay the ransom or lose their data permanently. Regular, secure backups remain one of the strongest defenses against ransomware.
Network Segmentation Prevents Spread
WannaCry spread quickly because many networks lacked segmentation. Separating critical systems reduces the chance of malware moving laterally across the network.
Awareness and Preparedness
Many organizations were caught unprepared. Training staff to recognize ransomware threats, creating response plans, and conducting regular drills are essential to minimizing damage.
How to Protect Against Ransomware Today
- Keep systems updated with the latest patches
- Use endpoint protection and intrusion detection tools
- Train employees on phishing and social engineering risks
- Implement strong backup and recovery strategies
- Monitor networks for unusual activity
Final Thoughts
WannaCry may have peaked in 2017, but ransomware attacks have only become more sophisticated since then. The core lesson is simple: staying prepared, updated, and resilient is the best way to defend against the next major cyber threat.