/usr/lib/x86_64-linux-gnu/libaunit.so is in libaunit2-dev 1.03-8.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libaunit.so.3
/usr/lib/x86_64-linux-gnu/libaunit.so.3