[jt2190]

For some context:

> The attacker and the victim must know each other and must have engaged in previous conversation on the IM app, which is a requirement for both the attack and the preparatory work.

> If the attackers perform enough tests to formulate an extensive dataset against a target, they could infer their position among a set of given possible locations in a city, like “home”, “office”, “gym”, etc., based on nothing else but the delivery notification delay