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  3. Microsoft Exchange Server SMTP Extended Verb Buffer Overflow Vulnerability

Microsoft Exchange Server SMTP Extended Verb Buffer Overflow Vulnerability

Risk

High

Date Discovered

April 12, 2005

Description

Microsoft Exchange Server is prone to a buffer overflow in the X-LINK2STATE SMTP extended verb. Successful exploitation could result in arbitrary code execution.

Technologies Affected

  • Microsoft Exchange Server 2000
  • Microsoft Exchange Server 2000 SP1
  • Microsoft Exchange Server 2000 SP2
  • Microsoft Exchange Server 2000 SP3
  • Microsoft Exchange Server 2003
  • Microsoft Exchange Server 2003 SP1

Recommendations

Block external access at the network boundary, unless external parties require service.

Block access to the vulnerable service at the network perimeter. Restrict external access to trusted computers and networks.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.

Deploy a network intrusion detection sensor between the affected service and the network perimeter. Audit the logs regularly for indications of potential attacks.

Run all software as a nonprivileged user with minimal access rights.

If possible, run the SMTP service as an unprivileged user with minimal access rights. This will limit the consequences of successful exploitation of this and other latent vulnerabilities.

Implement multiple redundant layers of security.

If possible, place the vulnerable server inside the network firewall and use an SMTP gateway to relay mail to the vulnerable server. Allow the vulnerable server to accept connections only from the SMTP gateway.
Microsoft has released updates to address this issue in supported versions.

Credits

Discovery is credited to Mark Dowd and Ben Layer.
Copyright © Symantec Corporation.
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from secure@symantec.com.

Disclaimer
The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
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