Introduction

Your customers and your staff make decisions based on what a web page, an application, or an equipment panel shows them. They allocate resources, approve payments, reset credentials, read balances, and shut down equipment on that basis. The systems behind those interfaces then carry out what was decided, often with no further authorization. Protecting those interfaces is as important as protecting the systems they drive.

Browsers, mobile apps, point-of-sale terminals, operator consoles, kiosks and vehicle displays all build the interface on the user's device in real time, pulling code, content, and resources from external providers as they go. Your own developers have coded part of the application. External suppliers control the rest, and their code and assets run with the same privileges. Any of those suppliers can change the resource it returns, at any time, to some users and not others. There is no easy patch, because nothing is malfunctioning: client-side rendering is the modern approach for building user experiences on demand, in real time, on the user's device. Attack the Glass is the vulnerability this design creates, and no patch removes it, so an organization reduces it instead.

Remediation sorts into three groups by what each change costs to make. An engineering team can act alone on the first group: inventory what loads, remove what nobody will vouch for, pin and constrain what stays, and put a manual procedure where no technical control reaches. The second group waits on an engineering cycle or a procurement round: assembling less on the client, governing the pipeline that feeds the build, extending browser-grade controls to the surfaces that are not browsers, and establishing who owns and operates each remaining supplier. The third group is not project work at all, and lapses without a named owner and a review date: architecture standards, continuous ownership monitoring, contract terms, and metrics.

None of it shows anyone what actually ran on a customer's device. Current client-side platforms provide no way to monitor what gets built there, and after the fact there is usually nothing left to examine. That limit is real, it is stated plainly at every measure, and The Residual sets out what would have to exist to close it. Start with removal, on every surface, because a component you never took on cannot be sold to someone else, cannot be compromised, and cannot quietly start returning something different.