These days security-sensitive business application systems are developed and maintained by more than one software engineer some of which may be unethical or malicious. Unethical software engineers can insert malicious code to the systems or maliciously change the existing code in the systems to gain personal benefits. As the result security of the business application systems can be compromised. This paper describes an approach to detecting malicious code created by malicious software engineers in components. This paper is an extension to our previous work detecting malicious code attacking security-sensitive information within a component. In particular this paper focuses on detecting malicious code in a component that intrudes security-sensitive information in different components in an application. For this an application system monitor(s) is designed to detect intrusion between components using the business process encapsulated in the monitor(s). The proposed approach is applied to the ATM system and B2B electronic commerce system to evaluate the performance.