Researchers call it a flaw or a bug. Though on a closer look it seems like an overlooked design and functionality issue. Irrespective, until recently WhatsApp was leaking phone numbers and profile photos of users through a “flaw” in the app. Security researchers have discovered that due to an issue with the app’s rate limiting in the contact discovery tool, someone might have scrapped phone numbers of almost all WhatsApp users and profile photos of a chunk of users without anyone coming to know about it.

A team of researchers from the University of Vienna managed to extract 3.5 billion phone numbers using what they describe as a “simple” technique that exploited WhatsApp’s contact-discovery system.

The researchers explained that the flaw was in the mechanism that checked whether a phone

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