According to a report by Rolling Stone, this information came from a leaked document of FBI (Federal Bureau of Investigation). The document has shown that Facebook -owned WhatsApp and Apple’s assessment gives the most information to the FBI, which FBI can legally get from any messaging app.
The document states that WhatsApp, IMES and Line App, all offered “Limited” messages content on the legal request of FBI. Apart from this, these platforms voluntarily offered ‘some’ data. At the same time, apps like Sign, Telegram, Threema, Viber, WeChat and Wickr did not disclose the message content. According to the information, the popular Android messaging app i.e. WhatsApp shares only the basic subscriber record.
In easy words this means that FBI is capable of acquiring address book data from both its ‘target’ and their contacts. The FBI app can also track the source of the message sent from the app and its destination. Meaning, if you have saved the contact information of FBI target, then your address book is also available to FBI. The situation is worse in terms of IMESSAGE service. If IMESSAGE users backup their messages on iCloud, then FBI has their message content.