  In security protocol analysis, the traditional choice to consider a single
Dolev-Yao attacker is supported by the fact that models with multiple
collaborating Dolev-Yao attackers have been shown to be reducible to models
with one Dolev-Yao attacker. In this paper, we take a fundamentally different
approach and investigate the case of multiple non-collaborating attackers.
After formalizing the framework for multi-attacker scenarios, we show with a
case study that concurrent competitive attacks can interfere with each other.
We then present a new strategy to defend security protocols, based on active
exploitation of attack interference. The paper can be seen as providing two
proof-of-concept results: (i) it is possible to exploit interference to
mitigate protocol vulnerabilities, thus providing a form of protection to
protocols; (ii) the search for defense strategies requires scenarios with at
least two attackers.
