According to my tests, this one should react on an exploit attempt:
Code:
Ctcp *:dcc send "*:*:{
  if $0 > 41 {
    echo -ta Congratulations! $nick just tried to exploit you.
  }
}

Add /halt after the /echo if you don't want the default error to appear in the status window.

(Note to v6-6.11 users: this will not prevent your mIRC from crashing :tongue:)