WhatsApp hacking has never been easy. Hacker suffers a lot coz WhatsApp uses very complicated encryption method which don't make WhatsApp hacking not vulnerable to any kind of attack. So the WhatsApp is much more safer than any other chatting platform available. So hacking WhatsApp through external hacking attacks makes it impossible for any external attack like SQL injection etc.
But you can hack someone's WhatsApp by physical hacking.
By physical hacking I mean hacking someone's mobile device. There are some websites which claims that by buying their product you can hack WhatsApp chat of someone's. But this nothing but a fraud so never ever by those products coz those are just fraud to loot people we are still waiting for that super genius programmer.
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