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WannaCry Ransomware Attack

A worldwide cyberattack by the WannaCry ransomware cryptoworm.

What happened

WannaCry infected hundreds of thousands of computers across 150 countries, encrypting data and demanding Bitcoin payments.

Technical mechanism

Exploited the EternalBlue vulnerability in Microsoft Windows (CVE-2017-0144).

Why it matters

One of the most widespread and damaging ransomware attacks in history.

Impact

Caused billions of dollars in damage, severely impacting the UK's NHS and other critical infrastructure.

Response

Microsoft released emergency patches for unsupported operating systems; a kill switch was discovered by Marcus Hutchins.

Defensive lessons

  • Importance of timely patching
  • Need for network segmentation
  • Risks of unsupported operating systems

Evidence register

  1. CISA — CISA Advisory on WannaCry (verified)