Big data is everywhere. Organisations now store and process data that is growing at an exponential rate. In the age of store-first-think-later, what if the data your organisation stored was actually your biggest threat and the enemy lurks within? What would the implications of 'evil' data be, how would you identify it and protect yourself whilst still relying on a fundamental component of daily business life? This presentation looks at the concept of data warfare, its roots in information warfare and how cyber security needs to evolve to become more data-aware and address this threat. Already we have seen the beginnings of data-based attacks and their ability to have significant impacts at not only an organisational level, but also at an economic level. In the age of quantum trading and businesses driven by big data analytics, organisations are becoming increasingly reliant on accurate, reliable and trustworthy data. Their biggest asset now also has the potential to become their biggest weakness.