Cryptic filenames in / of FC7T1

["Bernd Bartmann" <bernd bartmann gmail com>]

Hi,

I've found some cryptic named files in under / in FC7T1:

a-7QeJ
HXv5pB
xI6TYx
Zgu_vF

All files are 4 bytes long and contain "blat". Where do they come from?

Best regards,
Bernd.