During the last years, Wireless Sensor Networks (WSN) have been deployed at an accelerated rate. The complexity and low-power requirements of these networks have also been growing. Therefore, WSN developers are beginning to require efficient methodologies for network simulation and embedded SW performance analysis. These tools should also include security analysis. This security analysis has to evaluate the vulnerability of a WSN to the wide variety of attacks that these networks could suffer. WSN attacks could also affect power consumption and performance of the node's software, thus security analysis has to be integrated into a complete performance analysis framework. This work proposes a methodology to simulate the most common and dangerous attacks that a WSN can suffer nowadays. The impact of these attacks on power consumption and software execution time are also analyzed. This provides developers with important information about the effects that one or multiple attacks could have on the WSN, helping them to develop more secure software.