If it's a .png, it would open up in Microsoft Photos/eog/LXImage for me. Obviously some exploit could be found in there and any untrusted file is a risk, but it

If it's a .png, it would open up in Microsoft Photos/eog/LXImage for me. Obviously some exploit could be found in there and any untrusted file is a risk, but it won't open WinRAR. That's the whole point of why file extensions are so much better than any alternative.