This file is indexed.

/usr/lib/thunderbird/extensions/langpack-ko@thunderbird.mozilla.org.xpi is in thunderbird-l10n-ko 1:52.9.1-1~deb9u1.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/lib/thunderbird/extensions/../../../share/thunderbird/extensions/langpack-ko@thunderbird.mozilla.org.xpi