Flag: CTF{ICanReadDis}
You really went dumpster diving? Amazing. After many hours, SUCCESS! Between what looks like a three week old casserole and a copy of "Relative-Time Magazine", you found this important looking letter about the victims PC. However the credentials aren't readable - can you still obtain them?
attachment
The attached ZIP contains a PDF. Open it and see blacked out credentials:
Let's check for any hidden text by copying all text from the PDF to a text editor:
And the flag is visible.