/usr/src/virtualbox-guest-4.1.42/include/internal/ is in virtualbox-guest-dkms 4.1.42-dfsg-1+deb7u1.
This file is owned by root:root, with mode 0o755.
..
/usr/src/virtualbox-guest-4.1.42/include/internal/assert.h
/usr/src/virtualbox-guest-4.1.42/include/internal/initterm.h
/usr/src/virtualbox-guest-4.1.42/include/internal/iprt.h
/usr/src/virtualbox-guest-4.1.42/include/internal/lockvalidator.h
/usr/src/virtualbox-guest-4.1.42/include/internal/magics.h
/usr/src/virtualbox-guest-4.1.42/include/internal/memobj.h
/usr/src/virtualbox-guest-4.1.42/include/internal/process.h
/usr/src/virtualbox-guest-4.1.42/include/internal/sched.h
/usr/src/virtualbox-guest-4.1.42/include/internal/string.h
/usr/src/virtualbox-guest-4.1.42/include/internal/thread.h
/usr/src/virtualbox-guest-4.1.42/include/internal/time.h