/usr/share/afterstep/desktop/icons/ASBBlockDefault.xpm is in afterstep-data 2.2.12-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | <bevel border="4 4 4 4" solid="0">
<gradient angle="45" width="64" height="64"
colors="#5e686f #0c0d0e"/>
</bevel>
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