White residue at exhaust back box weld

[Beesza]

I had the car on jack stands last night and noticed white residue at one of the pipe welds leading into the back box.

Does anyone know what is going on here? Possibly the beginnings of a blowing exhaust?

 

[Haro]

Looks like exhaust paste.

 

[BumpyZ4]

That's a crappy looking weld on that one pipe. Clean it off and see if it comes back. If so, you have an exhaust leak at that weld.