Now, can anyone definitively prove that they are back doors and not mistakes or exploits? No. But that's thanks to the age old "Never ascribe to malice that which is adequately explained by incompetence."
Talk at black hat =/= everyones devices are de facto vulnerable. For as tech savy as this forum is, its surprising how many people are not well read up on security.
The summary of vulnerability is this - if you use a cellular network, your baseband chip vulnerability is next to irrelevant. Your location can be triangulated from radio signals, and its likely that there are messaging contacts and calls that are logged that use the respective celluar services.
Now for pure data transmission from a secure messaging app. Most of the communication for privacy is done using end to end encryption apps like Telegram. While those can be compromised, those require a direct targeted attack on the device, you cant just remotely do this over the internet.
Is that talk recorded somewhere?
Title: "Over the Air, Under the Radar: Attacking and Securing the Pixel Modem" Summary/Slides: https://www.blackhat.com/us-23/briefings/schedule/#over-the-... YouTube (48 minute): https://www.youtube.com/watch?v=QrkB_enz2Pk