Now, an attack ad campaign by Signal has shone some light on the opaque surveillance dragnet. The privacy-focused messaging app tried to buy “multi-variant targeted” ads on Instagram to show what parent company Facebook knows about its users. The campaign aimed to expose how Facebook’s array of services harvest user information to personalize ads. Advertisers can use the enormous range of data points to target audiences based on their location, age, demographics, interests, and behavior. [Read: 3 new technologies ecommerce brands can use to connect better with customers] The resulting adverts can be eerily intimate and potentially harmful. Just last week, researchers found that Facebook had allowed advertisers to target teenage children interested in smoking, gambling, and extreme weight loss. Signal’s plan was to use Facebook’s own tools to highlight these practices. “The ad would simply display some of the information collected about the viewer which the advertising platform uses,” Signal said in a blog post. “Facebook was not into that idea.” According to Signal, Facebook promptly disabled the ad account. Facebook denied that the account had been shut down and dismissed the ads as a publicity stunt. But Signal has maintained the claim. The company also shared examples of what Facebook ads would look like if they were open about the targeting. It might be merely a publicity stunt designed to attract more WhatsApp users to Signal, but it still effectively unmasks how ad targeting works. Greetings Humanoids! Did you know we have a newsletter all about AI? You can subscribe to it right here.