Can Someone Help Me Understand This Suspicious Batch Script I Found?

You could throw the random text into a base64 decoder tool for easier decoding. Just a warning though; you’ll want to assume that machine is compromised and should be wiped afterwards.

Just to add on, it appears this script downloads a fake JPEG from a server that actually contains malicious code. It could end up injecting this code into heavy CPU processes running on your machine. Proceed with caution!

This looks like a malware loader. I wouldn't run it outside of a quarantined environment, just to be safe.

If you ever give it to a paid version of ChatGPT, it might help decode this for you. But again, tread carefully.

The script sets a bunch of environment variables, many of which are parts of a base64 encoded string. A quick tip: take everything after the equals sign in each 'SET' command related to $encodedData, replace 'd@' with 'r', and decode it. You should be able to reveal the original script that way, but it's likely to still be malicious.