As part of a continuing research for evaluating threats posed for exposed attack surface, this study will provide a consolidated view of exploitability of vulnerable applications presenting a web attack surface of an organization exposed to an attacker. While testing and scanning technologies like Static Analysis Security Testing (SAST), Dynamic Analysis Security Testing (DAST), Application Ethical Hack (Penetration Testing), a monitoring technology like the Web Application Firewall (WAF) provides web traffic information of the number of transaction requests for every application under study. To ensure validity, reliability, and completeness of observation multiple applications must be observed. Research from a prior study is referenced that shows correlation between incoming WAF requests and existing vulnerabilities. Using correlation analysis, vulnerabilities metrics, and a threat model analysis help identify pathways to an attack. A vulnerability map-based attack tree can be developed using Common Weakness Enumeration (CWE) and Common Vulnerabilities and Exposures (CVE) information. The threat model analysis and vulnerability-based attack tree can help in simulation studies of possible attacks. This attack tree will show the linkages between vulnerabilities and a lineage pointing to how an attack could travel from the incoming WAF requests to deep down into the application code of exposed and existing, open vulnerabilities travelling laterally to create a more expanded attack crossing trust boundaries using application data flow.