/etc/ is in roundcube-plugins-extra 0.6-20111030.
This file is owned by root:root, with mode 0o755.
..
/etc/roundcube/
/etc/roundcube/plugins/
/etc/roundcube/plugins/compose_addressbook/
/etc/roundcube/plugins/compose_addressbook/config.inc.php
/etc/roundcube/plugins/dovecot_impersonate/
/etc/roundcube/plugins/dovecot_impersonate/config.inc.php
/etc/roundcube/plugins/jqueryui/
/etc/roundcube/plugins/jqueryui/config.inc.php
/etc/roundcube/plugins/markasjunk2/
/etc/roundcube/plugins/markasjunk2/config.inc.php
/etc/roundcube/plugins/sieverules/
/etc/roundcube/plugins/sieverules/config.inc.php
/etc/roundcube/plugins/sauserprefs/
/etc/roundcube/plugins/sauserprefs/config.inc.php
/etc/roundcube/plugins/zipdownload/
/etc/roundcube/plugins/zipdownload/config.inc.php