Ransomware is malware designed to virtually mimic the age-old crime of capturing items of value and demanding money for their safe return. Ransomware typically arrives via email or a backdoor, locks up valuable computer files, and is followed by a demand for compensation, often in Bitcoin or another cryptocurrency. The hacker promises a decryption tool on payment of the ransom – but there is never any guarantee of delivery or efficacy of the decryption tool.