QUOTE(No_Name @ Apr 7 2011, 04:06 PM)
No, you hit the huge wall thats called the signature.
No retail box will run unsigned code.
The original concept is very flawed , MS would know what it is in your XNA coded app , they would see that it is a backdoor and it wouldn't get on the market. On another note , i doubt XNA can really be used to code anything like that , it's like .NET for the 360 , and only works on a small set of the real SDK code base. You can't for instance do HV/Kernel calls with it , as far I know. Just having a loader built on XNA would not be enough , as the third-party stuff you want to run still has no signature and would not even be read as valid.
I run my own code on my retail box all the time. XNA requires you too pay before you can run the code , that is how it gets away with not being "signed" , or it is just signed with a local key derived from your 25 digit access code. I haven't tried my XNA game on anything but the retail box I built it on , but i would be willing to bet it will only run on that one, just like XDK software will only run on the console it was built for , until you Xextool it.
If you want find an exploit in the 360 reverse the kernel/HV and look for a bug , gamesave exploits , modifying system updates , anything simple is already covered in the HV unless you find another bug in it. These threads are always funny though ... bahahahaha. Even if you could exploit the 360 with XNA , you are breaking a lot of laws in the process , the whole point of the hacks is to do them with as little law breaking as possible. That isn't even really an exploit , more like the "ole switcharoo", if whatever it is didn't get put on the market place , then no one else would be able to run it anyway except whoever built it.