The Department of Homeland Security soon picked up on the CDC's success and incorporated zombies into its own planning and publicity operations.

WSJ: Why Zombies Are Everywhere

Since the beginning of the decade, cybercriminals have increasingly used malicious software to hijack unwitting PCs, turning about 20% of the world's computers into "zombies" that can be controlled and collected by the thousands into subservient criminal armies, according to research by security firm Trend Micro.

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