Penetration Testing mailing list archives
Re: TELNET and SMTP
From: "Levenglick, Jeff" <JLevenglick () fhlbatl com>
Date: Sun, 8 Jul 2007 17:11:42 -0400
Zach, Per standards, just about anybody can telnet to an smtp server on 25. (Do a dns lookup with MX set and telnet on 25 to the mail server) Some people use the server as outbound only and change the listen port to something they know. What they should do and it sounds like they did is restrict who is allowed to use the server to relay mail. (Relay-domain file ...ect) If you have OS access just read that file and you can see who is allowed to relay. Other security options include turning off commands link finger. (Sendmail option called goaway and a few other options) The big rule is to turn off the deamon if the server is not going to be used. -----Original Message----- From: listbounce () securityfocus com <listbounce () securityfocus com> To: pen-test () securityfocus com <pen-test () securityfocus com> Sent: Sun Jul 08 00:58:57 2007 Subject: RE: TELNET and SMTP Zach, Just out of interest, you state that you weren't able to send an e-mail. Were the source or destination addresses within your client's domain? Try sending an "internal" email and see if you get the same response. If not, then this can be used to send spoofed mail within the organisation.... e.g. from HR to an employee supposedly firing them, or from the CEO to the cute secretary in one of the departments harassing her sexually (the list goes on). -----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of wymerzp () sbu edu Sent: 07 July 2007 22:31 To: pen-test () securityfocus com Subject: TELNET and SMTP Hello all, I'm looking at a client's site and they have unprotected access to port 25 (i.e. I can telnet to it and issue commands). When I attempt to send an email I get this message '553 Relaying is not supported'. My question is two-fold: 1)What could I do with the unprotected SMTP access if I can't send mail. 2)What purpose do you believe that the SMTP service provides? Does the SMTP simply recieve!?!? Thank you all, Zach ------------------------------------------------------------------------ This List Sponsored by: Cenzic Swap Out your SPI or Watchfire app sec solution for Cenzic's robust, accurate risk assessment and management solution FREE - limited Time Offer http://www.cenzic.com/wf-spi ------------------------------------------------------------------------ ------------------------------------------------------------------------ This List Sponsored by: Cenzic Swap Out your SPI or Watchfire app sec solution for Cenzic's robust, accurate risk assessment and management solution FREE - limited Time Offer http://www.cenzic.com/wf-spi ------------------------------------------------------------------------ ----------------------------------------- This e-mail message is private and may contain confidential or privileged information.
Current thread:
- Re: TELNET and SMTP, (continued)
- Re: TELNET and SMTP StaticRez (Jul 07)
- Re: TELNET and SMTP Marco Ivaldi (Jul 09)
- Re: TELNET and SMTP Hans-J. Ullrich (Jul 07)
- Re: TELNET and SMTP rajat swarup (Jul 07)
- RE: TELNET and SMTP Richard Lane (Jul 08)
- Re: TELNET and SMTP A. Tom McFrog (Jul 08)
- Re: TELNET and SMTP AdamT (Jul 08)
- RE: TELNET and SMTP Thomas W Shinder (Jul 07)
- RE: TELNET and SMTP Levenglick, Jeff (Jul 09)
- RE: TELNET and SMTP Russell Butturini (Jul 09)
- RE: TELNET and SMTP Levenglick, Jeff (Jul 09)
- Re: TELNET and SMTP Levenglick, Jeff (Jul 08)
- Re: TELNET and SMTP StaticRez (Jul 07)