/etc/X11/app-defaults/XLogo is in x11-apps 7.7+5+nmu1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | XLogo*iconPixmap: xlogo32
XLogo*iconMask: xlogo32
XLogo*baseTranslations: #override \
<Key>q,<Key>Escape: quit()
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