Explainer: Why ransomware is so dangerous and hard to stop

Ransomware scrambles the target organisation’s data with encryption. The criminals leave instructions on infected computers for negotiating ransom payments. Once paid, they provide decryption keys for unlocking those files. — 123rf

Recent high-profile "ransomware” attacks on the world’s largest meat-packing company and the biggest US fuel pipeline have underscored how gangs of extortionist hackers can disrupt the economy and put lives and livelihoods at risk.

Last year alone in the US, ransomware gangs hit more than 100 federal, state and municipal agencies, upwards of 500 health care centres, 1,680 educational institutions and untold thousands of businesses, according to the cybersecurity firm Emsisoft. Dollar losses are in the tens of billions. Accurate numbers are elusive. Many victims shun reporting, fearing the reputational blight.