28th Feb 2003 [SBWID-6031]
COMMAND
ISMAIL remote buffer overrun
SYSTEMS AFFECTED
ISMAIL v 1.25 & v 1.4.3
PROBLEM
In Mark Litchfield [[email protected]] of NGSSoftware Insight
Security Research advisory [#NISR27022003] :
http://www.ngssoftware.com
--snipp--
ISMail is a powerful yet easy to use mail server for Windows
95/98/ME/NT/2000 & XP. It supports complete email service for both
home and office use, and runs on a dedicated or a shared machine
Details
*******
There exists a buffer overrun vulnerability in the SMTP service offered
by ISMAIL. By supplying long Domain name values in either the MAIL
FROM: or RCPT TO: values, an attacker can overwrite the saved returned
return address on the stack. As ISMAIL runs as a LOCALSYSTEM account,
any arbitrary code executed on the server being passed by an attacker
will run with system privileges. If no code is supplied, ISMAIL will
simply crash leaving a file in the outgoing message folder which will
immediately trigger the error once ISMail is restarted.
SOLUTION
The vendor has fixed the problems using the following:
ISMail 1.4.5 (and subsequent versions) accept domain names up to 255
characters in length. Domain names exceeding this length in the 'mail
from' and 'rcpt to' commands will result in a response of: '501 Syntax
error in parameters' Further, SMTP 'mail from' and 'rcpt to' command
lines exceeding 1024 characters (including the CRLF) will result in a
response of: '500 Line too long'
The fix is available from http://instantservers.com/download/ism145.exe
Despite this is a BETA release, if you are running ISMAIL version 1.4.3
or below, NGS recommend upgrading to the BETA version to protect
yourself from possible attacks.
--snap--