hacks like these, where you go from a PDF to full persistence, require a chain of exploits. Pegasus, the iOS malware that made the news awhile ago, used a chain of 3 exploits like this:

   [ Stage 1: Safari/WebKit ] ──> [ Stage 2: KASLR Bypass ] ──> [ Stage 3: Kernel Execution ]
     (Memory Corruption/RCE)        (Kernel Info Leak)            (UAF Privilege Escalation)