In the competitive economic market the demand of secured and reliable system is increasing day by day. A successful system development is possible by consider equally both functional and nonfunctional requirement. But practically nonfunctional requirements are not identifying as like functional requirement. There are few generic requirements for a system like auditability, extensibility, maintainability, performance, portability, reliability, security, testability, usability and etc. among them security is very vital issue for system development. The security of web based application is vulnerable now a days. For this reason the importance of web based application security is growing over the time. Very often the system fails because of without incorporating the appropriate security specific-process. Our proposed model elicits the system security in a systematic way during requirement analysis phase. Using use case and questionnaires table our model elicits the security requirements of a system. We use Point of Sale System as a case study to identify its security.