Someone on the security mailinglist Full-Disclosure has posted an interesting warning regarding proof-of-concept exploit code. It seems that multiple published exploits have been replaced with more malicious versions by unknown attackers.
The attackers replaced the shellcode in the demo exploits (which usually opens a root-shell) with more malicious versions like '
rm -rf /*'. As such shellcode usually consists of hex-encoded assembler instructions, most people don't have the slightest chance to understand it, and hence cannot verify what it really does. People who want to "just try out whether I'm vulnerable", might end up with a wiped hard drive (or worse).
The lesson (one of them, that is) we should learn here is to never execute any code we don't trust and/or fully understand.