Consumer mobile spyware apps covertly monitor a user's activities (i.e., text messages, phone calls, e-mail, location, etc.) and transmit that information over the Internet to support remote surveillance. Unlike conceptually similar apps used for state espionage, so-called "stalkerware" apps are mass-marketed to consumers on a retail basis and expose a far broader range of victims to invasive monitoring. Today the market for such apps is large enough to support dozens of competitors, with individual vendors reportedly monitoring hundreds of thousands of phones. However, while the research community is well aware of the existence of such apps, our understanding of the mechanisms they use to operate remains ad hoc. In this work, we perform an in-depth technical analysis of 14 distinct leading mobile spyware apps targeting Android phones. We document the range of mechanisms used to monitor user activity of various kinds (e.g., photos, text messages, live microphone access) — primarily through the creative abuse of Android APIs. We also discover previously undocumented methods these apps use to hide from detection and to achieve persistence. Additionally, we document the measures taken by each app to protect the privacy of the sensitive data they collect, identifying a range of failings on the part of spyware vendors (including privacy-sensitive data sent in the clear or stored in the cloud with little or no protection).

Intimate partner abusers use technology to track, monitor, harass, and otherwise harm their victims, and prior work reports that victims have few resources for obtaining help with such attacks. This paper presents a qualitative analysis of data from a field study of an approach to helping survivors of intimate partner violence (IPV) with technology abuse. In this approach, called clinical computer security, a trained technologist performs a face-to-face consultation with an IPV survivor to help them understand and navigate technology issues. Findings from consultations with 31 survivors, as well as IPV professionals working on their behalf, uncovered a range of digital security and privacy vulnerabilities exacerbated by the nuanced social context of such abuse. In this paper we explore survivor experiences with, and reactions to, the consultations, discussing (1) the ways in which survivors present their tech concerns, (2) the cooperative work required to guide survivors towards understanding probable causes of tech insecurity, (3) survivors' reactions to the consultations, particularly when security vulnerabilities or spyware are discovered, and (4) the role we play as consultants and interventionists in the complex socio-technical systems involved in mitigating IPV. We conclude by discussing some of the broad ethical and sustainability challenges raised by our work, and provide design opportunities for tech platforms to better support survivors of IPV.

Survivors of intimate partner violence increasingly report that abusers install spyware on devices to track their location, monitor communications, and cause emotional and physical harm. To date there has been only cursory investigation into the spyware used in such intimate partner surveillance (IPS). We provide the first in-depth study of the IPS spyware ecosystem. We design, implement, and evaluate a measurement pipeline that combines web and app store crawling with machine learning to find and label apps that are potentially dangerous in IPS contexts. Ultimately we identify several hundred such IPS-relevant apps. While we find dozens of overt spyware tools, the majority are "dual-use" apps - they have a legitimate purpose (e.g., child safety or anti-theft), but are easily and effectively repurposed for spying on a partner. We document that a wealth of online resources are available to educate abusers about exploiting apps for IPS. We also show how some dual-use app developers are encouraging their use in IPS via advertisements, blogs, and customer support services. We analyze existing anti-virus and anti-spyware tools, which universally fail to identify dual-use apps as a threat.