This paper considers security in wireless sensor networks (WSNs), focusing at the routing layer. We propose to analyze the behavior of some routing protocols according to attacks stemming from compromised nodes. Such malicious nodes could disrupt the routing functionality (node replication, Sybil attacks or Black-Grey-Sink holes). For such adversary models traditional cryptographic solutions are not enough by themselves but need to be completed by algorithmic solutions considering “beyond cryptography” approaches. Emphasizing internal attacks, with security features of routing in mind, we define the resiliency as the ability of a network to continue to operate in presence of k compromised nodes, i.e. the capacity of a network to endure and overcome internal attacks. In this context, we analyze four particular routing protocols (DSR, Gradient based, Greedy forwarding and Random walk routing). Using intensive simulations, we test their resiliency in presence of several compromised nodes in several adversary models.