Updates broke WordPress on my server (permission – sbox)

Hello,

I use debian squeeze with xen (vps.

Since i had hacking problem on my servers sbox/aufs has bee turn on.

I have set the permission’s script to executable.
This is what i do;
“find . -iname ‘*.php’ -exec chmod +x {} \;”

Work just fine.
The problem is that on update the permissions are changed by the update script.

As this is not a good behavior.
Is there a way to avoid the update script to touch my files permissions ?