/usr/lib/x86_64-linux-gnu/libcares.so is in libc-ares-dev 1.12.0-1+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libcares.so.2.2.0
/usr/lib/x86_64-linux-gnu/libcares.so.2.2.0