/usr/lib/firefox/ubuntukylin.cfg is in ubuntukylin-default-settings 1.4.4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | // Set default homepage
defaultPref("browser.startup.homepage", "data:text/plain,browser.startup.homepage=http://123.sogou.com/?11458");
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