Re: [Full-disclosure] Re: User Enumeration Flaw

That's called directory harvesting and it's hardly new. Most MTAs implement tarpitting of some sort, to limit VRFY or RCPT commands from a perticular IP to a certian threshold, before they start slowing them down.

There are also ways to silently drop (or accept with routing to /dev/null) a session for a recipient that isn't in an external database (eg: LDAP) -- and while this breaks the RFC, people do it anyway.

Ever looked at a Hotmail spam message? There will be 50 recipients ..

gbush@, hbush@, jbush@, kbush@, etc. the ones that bounce aren't real and get rejected. Those that don't come back get added as "valid" for the second round.

~Mike.

Dave Korn wrote:
Mar.Shatz@xxxxxxxxxxxxxxxx wrote:

whitehouse.gov MX 100 mailhub-wh2.whitehouse.gov
noone@box:~$
noone@box:~$ telnet mailhub-wh2.whitehouse.gov 25
Trying 63.161.169.140...
Connected to mailhub-wh2.whitehouse.gov.
Escape character is '^]'.
220 whitehouse.gov ESMTP service at Sun, 12 Feb 2006 11:29:38 -0500
(EST) helo jojo
250 esgeop03.whitehouse.gov Hello [xxx.xxx.xxx.xxx], pleased to meet
you mail from:bob@xxxxxxx
250 2.1.0 bob@xxxxxxxxxx Sender ok
rcpt to:gbush@xxxxxxxxxxxxxx
550 5.1.1 gbush@xxxxxxxxxxxxxxxxx User unknown
rcpt to:president@xxxxxxxxxxxxxx
250 2.1.5 president@xxxxxxxxxxxxxxxxx Recipient ok
quit
221 2.0.0 esgeop03.whitehouse.gov closing connection
Connection closed by foreign host.

User enumeration at the whitehouse



Tell DHS at once! What would happen if Al-Qaeda could figure out that there was a president in the whitehouse?


cheers,
DaveK
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