In mobile ad hoc networks (MANETs), multihop transmissions rely on nodes collaboration to correctly route and forward packets to their final destination. However, collaboration of intermediate nodes is not guaranteed and non-collaborative nodes may drop packets they are asked to forward. Such behaviour, known as packet dropping, results of nodespsila selfishness or maliciousness and has dramatic effects on networks performances. Most of proposed solutions to counter packet dropping are either based on trust management or multipath routing, but no solution combines both trust management and multipath routing. Adaptive Secured Multipath for Ad hoc networks (ASMA) is a security framework which adapts security to the application requirements; evaluates trustworthy relationship based on localized trust model and efficiently combines multipath routing into trust management. In this paper we study ASMA performance against the most classical and simple packet dropping attack: Black Hole attack. Aiming to evaluate ASMA in dense networks, we use a realistic scenario representing a subway environment which brings interesting features and may be a prolific context for MANET application development. Through simulations we compare the performances of DSR and ASMA associated to DSR in attacked pure MANETs. Simulation results illustrate that ASMA-DSR outperforms DSR under different attack configurations and is totally adapted for dense and large networks.