Correlation Model of Worm Propagation on Scale-Free Networks

The problem of network worms is worsening despite increasing efforts and expenditure on cyber-security. Worm propagation is a random process that creates a complex system of interacting agents (worm copies) over the propagation medium – a scale-free graph, representing real-world networks. Understanding the propagation of network worms on scale-free graphs is the first step towards devising effective techniques for worm quarantining. After presenting the drawbacks of existing mean-field models, we develop a pair-approximation (correlation) model of worm propagation that employs the salient network characteristics – order, size, degree distribution, and transitivity. Inclusion of the transitivity shows significant improvement over existing pair-approximation models. The validity of the model is confirmed by comparing the numeric solution of the model to results from our individual-based simulation. Our model demonstrates that the network structure has considerable impact on the propagation dynamics when the worm uses local propagation strategies.