Public and private Infrastructure as a Service (IaaS) clouds are widely used by individuals and organizations to provision flexible virtual computing resources on demand. Virtual Network Embedding (VNE) algorithms are employed in this context to provide an automated resource assignment. With multiple involved parties, security-aware Virtual Machine (VM) placement becomes highly relevant for production environments. Moreover, VNE algorithms should also consider the security requirements of the interconnections between VMs, thereby extending the problem to networks. This paper discusses security requirements of Virtual Networks (VNs) and shows how they can be modeled in VNE to map them to the provided security mechanisms in the physical network. The paper also presents an implementation of this security-aware VNE model in the public simulation platform ALEVIN, demonstrating the applicability with a realistic use case of such a model.