Bump in the Ether: Mobile Phones as Proxies for Sensitive Input

User-space malware such as keyboard sniffers, spyware, and Trojans represent a significant threat to today’s desktop computing environment. Users have little assurance that such malware cannot observe their input to a particular application. In this paper, we present Bump in the Ether (BitE), an approach for preventing malware from accessing sensitive user input and providing the user with additional confidence that her input is being processed as desired. Rather than preventing malware from running or detecting already-running malware, we facilitate user input that bypasses common avenues of attack. User input traverses a trusted tunnel from the input device to the application. This trusted tunnel is implemented using a trusted user device working in tandem with a TCG-compliant host platform. The user device verifies the integrity of the host platform and application, provides a trusted display through which the user selects the application to which her inputs should be directed, and encrypts those inputs so that only the application can decrypt them. We describe the design and implementation of BitE, with emphasis on both usability and security issues.