Here's what I got so far, though I might not be doing this right...
Trigger: Touch - No CR modifier
Reset Type: Automatic - No CR modifier
Confusion: +4
CR 4 so far. Now, a Search DC of 30 or higher is +2 to CR, and if this one can't be found in a search check at all, then I guess a 4 would be appropriate. So...
No Search: +4
Now, a Disable Device DC of 30 or higher is also +2, so again, maybe another +4.
No Disable: +4
The trap would have a CR 12, but I wouldn't actually give any XP for this trap at all. Why? First of all, it can't be disabled. Secondly, nobody can even identify it for what it is. Basically, there is nothing to learn from this trap except "Be careful what you touch, even when it doesn't appear to be a trap at all, even to a diety".
My CR's may very well be wrong though, and I'm betting they are, but I still wouldn't give XP for the trap.