This is for searching for a given string.
I paste a screenshot of the prototype here:
https://i.imgur.com/8IxxjE6.png. It shows that the string
0x00 0x04 0x00 0xE8 0x02 0x00 is common to 8 files out of the sample set.
And here it is, viewed in a hex editor:
https://i.imgur.com/I06WEu7.png.