Весёлый EXE (Funny EXE)

hackerlab

Task: a MinGW PE32+ that trolls with meme wallpapers/sounds; the real flag check runs from the CRT startup after main returns, talking a custom TCP protocol to a hardcoded C2. Solution: locate the hidden post-main function via xrefs, replay the PASS protocol to a live server to obtain the keystream + encrypted flag, then invert the self-inverting per-byte cipher by brute-forcing printable chars.