/usr/lib/x86_64-linux-gnu/libctemplate.so is in libctemplate-dev 2.3-3+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libctemplate.so.3.0.0
/usr/lib/x86_64-linux-gnu/libctemplate.so.3.0.0