/usr/lib/ipsec/libstrongswan.so is in libstrongswan 5.3.5-1ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ipsec/libstrongswan.so.0.0.0
/usr/lib/ipsec/libstrongswan.so.0.0.0