If it's just old SQL injection, then they are pretty low grade hackers, but anybody can learn that shit these days on TryHackMe or something.
Holy kek. That's great, kudos to them. That's an interesting little exploit. Metasploit has a PostScript exploit like that iirc, but I'm not sure if it's suid. Anyways, i applauded them. Also brings to mind how many other vulnerabilities 4chan probably has that are easy to exploit.