Many methodologies exist to assess the security risks associated with unauthorized leakage, modification and interruption of information for a given organisation. We argue that the traditional orientation of these methodologies, towards the identification and assessment of technical information assets, obscures key risks associated with the cultivation and deployment of organisational knowledge. Our argument is developed throughan illustrative case study in which a well-documented methodology is applied to a complex data back-up process. This process is seen to depend, in subtle and often informal ways, on knowledge to sustain operational complexity, handle exceptions and make frequent interventions. Although typical information security methodologies identify people as critical assets, we suggest a new approach might draw on more detailed accounts of individual knowledge, collective knowledge, and their relationship to organisational processes. Drawing on the knowledge- management literature, we suggest mechanisms to incoscope of information security risk methodologies.