The paper presents a ready-to-use security assessment framework for wireless sensor networks (WSNs). The parameters in the proposed security assessment framework perform independent security assessment of WSNs and of their applications. Our proposed framework uses actual responses of the entities (such as nodes, communication link and network response) to assign numerical values for security assessment of WSNs. The method for calculating the optimal values for each security parameter of the framework is also discussed. Our proposed framework is designed to avoid unwanted impacts of the complexities of security algorithms, communication protocols and strong cryptography. Usually, the complexity of algorithms disguises the actual assessment of the WSN, but the independence of the proposed framework from these security-disguising objects makes this framework better than other assessment frameworks in terms of scalability.