2011 stock exhaust issue

i noticed that I was getting a lot of soot build up on the left hand exhaust pipe and now upon closer inspection I can see one of the rivets holding the tip of the exhaust looks bent and there are signs of soot down the pipe next to it. Is this something that can be sorted?

 

bit of an update, I found a bargain set of unused silencers and back pipe on eBay taken from a new bike so am going to fit them tomorrow. They have come complete with new clamps and mesh gaskets. Do you just clamp them directly onto the existing pipe or do you need some form of exhaust putty?

Any advice welcome as I've never tacked this before.

 

Cheers guys

Fitted the new ones this morning and all went well (unusual for me!). However when I started her up and was checking for leaks around the gaskets I realised that each silencer box appears to have 2 small holes front and back underneath which look like they should have a rivet in? Air was clearly blowing out of each of them. I had a look at the old ones I took off and they seem to have the same, are these breather holes or something that are meant to be there? I took some pictures.