In a threat landscape dominated by malware that is designed to be as unobtrusive as possible, ransomware stands out as a blunt instrument in the hands of cybercriminals. David Emm explains what ransomware is, how it works, what techniques cybercriminals use, and what organisations need to do to secure their data. The session was part of Secure South West 7 on 5 October 2016. [Released under Creative Commons Attribution-NonCommercial-ShareAlike 2.0 UK: England & Wales licence.]