/usr/lib/x86_64-linux-gnu/libxtables.so is in libxtables-dev 1.6.1-2ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libxtables.so.12.0.0
/usr/lib/x86_64-linux-gnu/libxtables.so.12.0.0