  This paper presents a specific man-in-the-middle exploit: Ambient Tactical
Deception (ATD) in online communication, realized via a malicious web browser
extension. Extensions manipulate web content in unobtrusive ways as ambient
intermediaries of the overall browsing experience. In our previous work, we
demonstrated that it is possible to employ tactical deception by making covert
changes in the text content of a web page, regardless of the source. In this
work, we investigated the application of ATD in a web-based email discourse
where the objective is to manipulate the interpersonal perception without the
knowledge of the involved parties. We focus on web-based email text because it
is asynchronous and usually revised for clarity and politeness. Previous
research has demonstrated that people's perception of politeness in online
communication is based on three factors: the degree of imposition, the power of
the receiver over the sender, and the social distance between them. We
interviewed participants about their perception of these factors to establish
the plausibility of ATD for email discourse. The results indicate that by
covertly altering the politeness strategy in an email, it is possible for an
ATD attacker to manipulate the receiver's perception on all of the politeness
factors. Our findings support the Brown and Levinson's politeness theory and
Walther's hyperpersonal model of email communication.
