/usr/share/dbus-1/services/com.ubuntu.sso.service is in ubuntu-sso-client 13.10-0ubuntu11.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | [D-BUS Service]
Name=com.ubuntu.sso
Exec=/usr/lib/ubuntu-sso-client/ubuntu-sso-login
|