This paper discusses the use of Aspect-Oriented Programming (AOP) as an efficient way to handle cloud computing frontend security concerns. Without AOP, the necessary security code would be mixed with the business logic that the cloud service provider implements. This makes the maintenance of both code and business logic tedious and prone to errors. The proposed aspect-oriented approach in this paper is built upon a Web services frontend to the cloud service. Three types of context are taken into account when tuning the aspects (security services). The contexts contain various details on the environment of the Cloud and the Web services, which permit activating the necessary aspects in response to these details. A set of experiments validating this approach, are also reported in this paper.