An anonymous reader writes: Whatsapp differentiates itself from parent company Facebook by touting its end-to-end encryption. "Some of your most personal moments are shared with WhatsApp," the company writes on its website, so "your messages, photos, videos, voice messages, documents, and calls are secured from falling into the wrong hands." But WhatsApp members may not be aware that when using the app's Group Chat feature, their data can be harvested by anyone in the group. What is worse, their mobile numbers can be used to identify and target them. WhatsApp groups are designed to enable groups of up to 256 people to join a shared chat without having to go through a central administrator. Group originators can add contacts from their phones or create links enabling anyone to opt-in. These groups, which can be found through web searches, discuss topics as diverse as agriculture, politics, pornography, sports, and technology. Not all groups have links, but in those that do, anyone who finds the link can join the group. While all new joining members are announced to the group, they are not required to provide a name or otherwise identify themselves. This design could leave inattentive members open to targeting, as a new report from European researchers shows. WhatsApp is used by more than 1.2 billion users worldwide.
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