AUSCERT External Security Bulletin Redistribution

                  ESB-2004.0147 -- eEye Security Bulletin
                 ZoneLabs SMTP Processing Buffer Overflow
                             23 February 2004


        AusCERT Security Bulletin Summary

Product:                ZoneAlarm 4.0 and later
                        ZoneAlarm Pro 4.0 and later
                        ZoneAlarm Plus 4.0 and later
                        ZoneLabs Integrity client 4.0 and later
Publisher:              eEye Digital Security
Impact:                 Denial of Service
                        Administrator Compromise
Access Required:        Remote

Comment: See also the Zone Labs Security Advisory at:

         Zone Labs has stated that "successful exploitation requires one 
         of the following scenarios and applies only to SMTP traffic:
         o A program listening on port 25/TCP (SMTP) of the target
           system. This condition is usually only present on SMTP servers.
           Zone Labs does not recommend using our client security products
           to protect servers.
         o A malicious program running on the protected system could
           trigger the buffer overflow and gain SYSTEM privileges if the
           user or administrator has given it permission to access the

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ZoneLabs SMTP Processing Buffer Overflow

Release Date:
February 18, 2004

Date Reported:
February 13, 2004

Medium (Local Privilege Escalation/Remote Code Execution)

ZoneLabs Inc.
Software Affected:
ZoneAlarm 4.0 and above
ZoneAlarm Pro 4.0 and above
ZoneAlarm Plus 4.0 and above
ZoneLabs Integrity client 4.0 and above

ZoneLabs provides a suite of desktop firewall products. Products in this
suite such as ZoneAlarm analyze incoming and outgoing email messages for
malicious or otherwise abnormal content. When ZoneAlarm examines
outgoing email messages a buffer overflow condition is presented when
they retrieve the destination email address from the message. An
attacker can exploit this vulnerability to elevate his privileges to
SYSTEM on any machine protected by a vulnerable ZoneLabs product. This
vulnerability can also be exploited remotely if an attacker can
manipulate the protected system into sending an outgoing email message.

Technical Description:
A stack based buffer overflow vulnerability within vsmon.exe can be
exploited to execute code with the context of the SYSTEM account. The
vulnerability exists within the component responsible for processing the
RCPT TO command argument. By specifying a large argument to the RCPT TO
command an internal stack based buffer can be overflowed within the
TrueVector Internet Monitor (vsmon.exe) process.

Retina Network Security Scanner has been updated to identify this

Vendor Status:
ZoneLabs was contacted and within only a few days they produced an
update to eliminate this vulnerability within their products. We would
like to give special recognition to the responsiveness of ZoneLabs in
creating a fix to protect their customers. 


Discovery: Riley Hassell

Related Links:
Retina Network Security Scanner - Free 15 Day Trial

All the other firewall vendors on our list.

Copyright (c) 1998-2004 eEye Digital Security Permission is hereby
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Please send suggestions, updates, and comments to:

eEye Digital Security

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