1 (edited by ozapien 2013-06-14 03:21:04)

Topic: Alias Domain Open Relay problem

==== Required information ====
- iRedMail version: 0.8.4
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL 1.6.0
- Linux/BSD distribution name and version: Ubuntu 12.04
- Related log if you're reporting an issue:
====

In a new installation I notice that if any spammer, fake "MAIL FROM:" command to a valid alias domain account it can relay mail without been authenticated.


A valid reject if try to relay with a domain account:
**************************************************************
Resolving hostname...
Connecting...
SMTP -> FROM SERVER:
220 mail01.domain.tld (Postfix). All Spam Is Reported. ESMTP
SMTP -> FROM SERVER:
250-mail01.domain.tld
250-PIPELINING
250-SIZE 15728640
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: postmaster@domain.tld
SMTP -> FROM SERVER:
250 2.1.0 Ok
RCPT TO: postmaster@domain.tld
SMTP -> FROM SERVER:
553 5.7.1 : Sender address rejected: not logged in
SMTP -> ERROR: RCPT not accepted from server: 553 5.7.1 : Sender address rejected: not logged in

Message sending failed.                                                #################   PERFECT... It's ok
**************************************************************

The problem when spammer use an alias domain in MAIL FROM: command
************************************************************
Resolving hostname...
Connecting...
SMTP -> FROM SERVER:
220 mail01.domain.tld (Postfix). All Spam Is Reported. ESMTP
SMTP -> FROM SERVER:
250-mail01.domain.tld
250-PIPELINING
250-SIZE 15728640
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: any_valid_user@domain-alias.tld
SMTP -> FROM SERVER:
250 2.1.0 Ok
RCPT TO: another_valid_user@domain.tld      # Or domain-alias.tld
SMTP -> FROM SERVER:
250 2.1.5 Ok
Sending Mail Message Body...
SMTP -> FROM SERVER:
354 End data with .
SMTP -> FROM SERVER:
250 2.0.0 Ok: queued as A897B1340DBD
Message completed successfully.                                             #################   Houston, we've had a problem!!!
************************************************************

2

Re: Alias Domain Open Relay problem

I cannot reproduce this issue. here's what i did (c6 is hostname of my virtual machine).

1) domain "a.cn" is a primary domain, postmaster@a.cn is a valid mail user.

$ telnet c6 25
Trying 172.16.244.131...
Connected to c6.
Escape character is '^]'.
220 c6.iredmail.org ESMTP Postfix
EHLO t.cn
250-c6.iredmail.org
250-PIPELINING
250-SIZE 15728640
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: postmaster@a.cn
250 2.1.0 Ok
RCPT TO: postmaster@a.cn
553 5.7.1 <postmaster@a.cn>: Sender address rejected: not logged in

2) domain "B.cn" is an alias domain of "a.cn", and of course postmaster@b.cn is an alias address of "postmster@a.cn".

$ telnet c6 25
Trying 172.16.244.131...
Connected to c6.
Escape character is '^]'.
220 c6.iredmail.org ESMTP Postfix
EHLO t.cn
250-c6.iredmail.org
250-PIPELINING
250-SIZE 15728640
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: postmaster@b.cn
250 2.1.0 Ok
RCPT TO: postmaster@b.cn
553 5.7.1 <postmaster@b.cn>: Sender address rejected: not logged in