  An encounter-based network is a frequently disconnected wireless ad-hoc
network requiring nearby neighbors to store and forward data utilizing mobility
and encounters over time. Using traditional approaches such as gateways or
firewalls for deterring worm propagation in encounter-based networks is
inappropriate. Because this type of network is highly dynamic and has no
specific boundary, a distributed counter-worm mechanism is needed. We propose
models for the worm interaction approach that relies upon automated beneficial
worm generation to alleviate problems of worm propagation in such networks. We
study and analyze the impact of key mobile node characteristics including node
cooperation, immunization, on-off behavior on the worm propagations and
interactions. We validate our proposed model using extensive simulations. We
also find that, in addition to immunization, cooperation can reduce the level
of worm infection. Furthermore, on-off behavior linearly impacts only timing
aspect but not the overall infection. Using realistic mobile network
measurements, we find that encounters are non-uniform, the trends are
consistent with the model but the magnitudes are drastically different.
Immunization seems to be the most effective in such scenarios. These findings
provide insight that we hope would aid to develop counter-worm protocols in
future encounter-based networks.
