Though AmIRC apparently is riddled with backdoors and security holes.
There's no backdoor that I can think of. AmIRC has two hidden features though:
- It's possible to query the serial number via specially crafted CTCP. This can be used to identify people using pirated versions.
- AmIRC refuses to DCC SEND its' keyfiles. That's reasonable enough measure I'd think.
Neither of these amounts to a backdoor or security hole IMHO.