Representing Humans in System Security Models:
An Actor-Network Approach

 

Wolter Pieters

University of Twente

Enschede, The Netherlands

w.pieters@utwente.nl

 

 

Abstract

 

System models to assess the vulnerability of information systems to security threats

typically represent a physical infrastructure (buildings) and a digital infrastructure (computers and networks),

in combination with an attacker traversing the system while acquiring credentials. Other humans are

generally not included, as their behavior is considered more difficult to express. We propose a

graph-based reference model for reasoning about access in system models including human actions,

inspired by the sociological actor-network theory, treating humans and non-humans symmetrically.

This means that humans can employ things to gain access (an attacker gains access to a room by

means of a key), but things can also employ humans to gain access (a USB stick gains access to a

computer by means of an employee), leading to a simple but expressive model. The model has the

additional advantage that it is not based on containment, an increasingly problematic notion in the

age of disappearing boundaries between systems. Based on the reference model, we discuss algorithms

for finding attacks, as well as examples. The reference model can serve as a starting point for

discussing representations of human behavior in system models, and for including human behavior

in other than graph-based approaches.

 

Keywords: actor-network theory, containment, hypergraphs, security modelling, socio-technical

systems, vulnerability analysis

 

Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA),

Vol. 2, No. 1, pp. 75-92, June 2011 [pdf]