Last week, LinkedIn published an indepth technical explanation of how their new LinkedIn Intro mobile product works on iOS. What Intro does is basically display LinkedIn data about your contacts directly in your email client – similar to what Rapportive did for gmail. It’s a cool app but the implementation details LinkedIn shared ignited an Internet firestorm, especially among the startup/hacker crowd.

How Intro works is it basically modifies the users normal iOS email client so that it connects through a LinkedIn proxy server instead of interacting with their webmail provider directly. What this does, is allow LinkedIn to dynamically modify a user’s email before it reaches their mail client, depending on if the user is connected to the sender on LinkedIn. From a IT security standpoint, introducing a third party that would sit between a user and the mail server they’re connecting to undoubtedly introduces a new attack vector but what really caught my interest was how LinkedIn was achieving this. In order to smoothly update the user’s proxy settings, LinkedIn is using a iOS feature known as Configuration Profiles.

I’m not familiar with the iOS SDK or APIs so this was the first time I’d heard about Configuration Profiles. In short, what they allow an app to do is install a set of settings on an iOS device – from email and web proxy settings to additional credentials and SSL keys. Configuration profiles are typically used in enterprise environments to allow a company’s IT department to quickly configure the settings on an employee’s iOS device. When provisioning a new device, IT would basically use the configuration profile to install things like a VPN, internal credentials, etc. So what’s the problem?

Well according to the LinkedIn post and comments from users that have used profiles before, the user experience of installing a profile which radically alters your iOS system settings is surprisingly unassuming. As a user, you click through a couple of prompts and boom, all of a sudden Safari is using a proxy server to fetch websites. So what nefarious things could you do by routing iOS mobile traffic through a proxy server? Unsolicited injected display advertising.

On the desktop web, unscrupulous extension developers have been monetizing their install base by injecting display ads into the browsing experience of their users for years. From companies like Bonzi Buddy to newer companies like PageRage, the model is tried, true, and profitable. However, on mobile there isn’t an obvious opportunity to inject ads and get access to the rapidly growing number of mobile web impressions. It seems like using configuration profiles would be the perfect vector to change this. Crapware iOS developers could quietly prompt their users to install a configuration profile to get access to “hot new features” and then surreptitiously start injecting display ads into websites on the proxy server.

I’m not familiar enough with iOS development to speak to how easy developing an app like this would be or if it would get past the app store approval process, but if it’s feasible someone is certainly going to do it. If anyone is familiar with an app already doing this, I’d love to know about it.

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