Browser-Based Covert Data Exfiltration

Current best practices heavily control user permissions on network systems. This effectively mitigates many insider threats regarding the collection and exfiltration of data. Many methods of covert communication involve crafting custom packets, typically requiring both the necessary software and elevated privileges on the system. By exploiting the functionality of a browser, covert channels for data exfiltration may be created without additional software or user privileges. This paper explores novel methods of using a browser's JavaScript engine to exfiltrate documents over the Domain Name System (DNS) protocol without sending less covert Hypertext Transfer Protocol (HTTP) requests.