In this paper, we define a process to model and simulate attack scenarios in networked environments. Known system vulnerability data, system configuration data, and vulnerability scanner results are associated to create exploitation graphs (e-graphs) which are used to represent attack scenarios. Experiments carried out in a cluster computing environment showed the usefulness of proposed techniques in providing in-depth attack scenario analyses for security engineering. Critical vulnerabilities can be identified by employing graph algorithms. Several factors were used to measure the difficulty in executing an attack. A cost/benefit analysis was used for more accurate quantitative analysis of attack scenarios. We have also shown how the attack scenario analyses better help deployment of security products and design of network topologies.