PoC Tool Tracks Device Status via WhatsApp & Signal Delivery Receipts

tom_doerr · x · 2026-08-13

An open-source project named Device Activity Tracker (5.1k Stars) demonstrates a severe privacy vulnerability in WhatsApp and Signal.

Based on the paper Careless Whisper from the University of Vienna, the tool measures the Round-Trip Time (RTT) of message delivery receipts. This allows an attacker to determine a target device's real-time status (active, standby, or offline) and infer sensitive activity patterns without any user interaction.

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