/usr/lib/x86_64-linux-gnu/libaunit.so is in libaunit3.7.2-dev 3.7.2-1+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libaunit.so.3.7.2
/usr/lib/x86_64-linux-gnu/libaunit.so.3.7.2