HTTP and HTTPS traffic recorded at the perimeter of an organization is an exhaustive data source for the forensic investigation of security incidents. However, due to the nested nature of today's Web page structures, it is a huge manual effort to tell apart benign traffic caused by regular user browsing from malicious traffic that relates to malware or insider threats. We present Hviz, an interactive visualization approach to represent the event timeline of HTTP and HTTPS activities of a workstation in a comprehensible manner. Hviz facilitates incident investigation by structuring, aggregating, and correlating HTTP events between workstations in order to reduce the number of events that are exposed to an investigator while preserving the big picture. We have implemented a prototype system and have used it to evaluate its utility using synthetic and real-world HTTP traces from a campus network. Our results show that Hviz is able to significantly reduce the number of user browsing events that need to be exposed to an investigator by distilling the structural properties of HTTP traffic, thus simplifying the examination of malicious activities that arise from malware traffic or insider threats.ISSN:1742-2876ISSN:1873-202