Email service has increasingly been outsourced to cloud-based providers and so too has the task of filtering such messages for potential threats. Thus, customers will commonly direct that their incoming email is first sent to a third-party email filtering service (e.g., Proofpoint or Barracuda) and only the "clean" messages are then sent on to their email hosting provider (e.g., Gmail or Microsoft Exchange Online). However, this loosely coupled approach can, in theory, be bypassed if the email hosting provider is not configured to only accept messages that arrive from the email filtering service. In this paper we demonstrate that such bypasses are commonly possible. We document a multi-step methodology to infer if an organization has correctly configured its email hosting provider to guard against such scenarios. Then, using an empirical measurement of edu and com domains as a case study, we show that 80% of such organizations making use of popular cloud-based email filtering services can be bypassed in this manner. We also discuss reasons that lead to such misconfigurations and outline challenges in hardening the binding between email filtering and hosting providers.

The Internet Routing Registry (IRR) is a set of distributed databases used by networks to register routing policy information and to validate messages received in the Border Gateway Protocol (BGP). First deployed in the 1990s, the IRR remains the most widely used database for routing security purposes, despite the existence of more recent and more secure alternatives. Yet, the IRR lacks a strict validation standard and the limited coordination across different database providers can lead to inaccuracies. Moreover, it has been reported that attackers have begun to register false records in the IRR to bypass operators' defenses when launching attacks on the Internet routing system, such as BGP hijacks. In this paper, we provide a longitudinal analysis of the IRR over the span of 1.5 years. We develop a workflow to identify irregular IRR records that contain conflicting information compared to different routing data sources. We identify 34,199 irregular route objects out of 1,542,724 route objects from November 2021 to May 2023 in the largest IRR database and find 6,373 to be potentially suspicious.

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).