/usr/share/icons/gnome-dust/24x24/apps/ is in gnome-dust-icon-theme 5.5.1-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/icons/gnome-dust/24x24/apps/Thunar.png
/usr/share/icons/gnome-dust/24x24/apps/alacarte.png
/usr/share/icons/gnome-dust/24x24/apps/application-x-remote-connection.png
/usr/share/icons/gnome-dust/24x24/apps/application-x-vnc.png
/usr/share/icons/gnome-dust/24x24/apps/compiz.png
/usr/share/icons/gnome-dust/24x24/apps/drakmenustyle.png
/usr/share/icons/gnome-dust/24x24/apps/file-manager.png
/usr/share/icons/gnome-dust/24x24/apps/fusion-icon.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-gmenu.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-mime-application-x-remote-connection.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-mime-application-x-vnc.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-panel-workspace-switcher.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-remote-desktop.png
/usr/share/icons/gnome-dust/24x24/apps/gnome-workspace.png
/usr/share/icons/gnome-dust/24x24/apps/kfm.png
/usr/share/icons/gnome-dust/24x24/apps/krfb
/usr/share/icons/gnome-dust/24x24/apps/menu-editor.png
/usr/share/icons/gnome-dust/24x24/apps/nautilus.png
/usr/share/icons/gnome-dust/24x24/apps/nautilus.xpm
/usr/share/icons/gnome-dust/24x24/apps/pcmanfm.png
/usr/share/icons/gnome-dust/24x24/apps/preferences-desktop-remote-desktop.png
/usr/share/icons/gnome-dust/24x24/apps/redhat-filemanager.png
/usr/share/icons/gnome-dust/24x24/apps/system-file-manager.png
/usr/share/icons/gnome-dust/24x24/apps/tightvnc
/usr/share/icons/gnome-dust/24x24/apps/tsclient
/usr/share/icons/gnome-dust/24x24/apps/tsclient.xpm
/usr/share/icons/gnome-dust/24x24/apps/vinagre.png
/usr/share/icons/gnome-dust/24x24/apps/workspace-switcher.png
/usr/share/icons/gnome-dust/24x24/apps/xfce-filemanager.png
/usr/share/icons/gnome-dust/24x24/apps/xfce4-menueditor.png
/usr/share/icons/gnome-dust/24x24/apps/xfce4-workspaces.png