Without actually having eyes on the evaluation we can’t make a blanket statement for your solution. That said, you can attach to structure 'behind' rock facade. Assuming the ‘rock’ is cosmetic and not structural you can ‘core drill’ though the rock to secure to ‘structure’ on the other side. If the rock wall is structural – then review with a qualified engineer to determine its load capacity and structural value for attachment design. You can usually find attachment hardware suitable for your structure and materials. Make sure your method will meet with your local codes.
Codes may read: 'In the case a precast stone, brick or pavers be found on the exhisting wall or floor - anchors shall be long enough to reach the main structure behind such panels. No embedment into stucco shall be permitted.'
Hurricane Preparedness Expert