extensions is a forensics puzzle worth 150 points.

The description to this puzzle is as follows:

This is a really weird text file TXT? Can you find the flag?

A file flag.txt is provided. Opening it with notepad shows a PNG header:

file confirms that this is a PNG file:

% file flag.txt
flag.txt: PNG image data, 1697 x 608, 8-bit/color RGB, non-interlaced

I renamed this to flag.png and opened it to get the flag: