EMC Dantz Retrospect 7 Backup client DoS Vulnerability

iDefense Security Advisory 03.02.06
http://www.idefense.com/application/poi/display?type=vulnerabilities
March 02, 2006

I. BACKGROUND

EMC Dantz Retrospect is a network backup client designed for small
to mid-sized businesses. Dantz protects millions of computers world
wide by providing enterprise class backup protection for servers,
notebooks, and business critical applications.

More information on this software package can be found on the
vendors site:

  http://www.dantz.com

II. DESCRIPTION

The Dantz Retrospect 7 backup client listens on TCP port 497 for
commands from the central backup server. Sending a specially crafted
malformed  packet to this socket can force the backup client to
terminate.

This allows for an unauthenticated attacker to effectively disable the
network backup services for a target network.

III. ANALYSIS

Exploitation appears to be limited to a DoS only condition. From debug
log information it appears that the packet corruption is detected by
the application which then decides to terminate rather than discard the
data. The following type information may be found in debug logs of
exploited machines

Assertion failure at \retroclient\Win\winutil.c-1201
DebugFail: Client Terminated
Retrospect Client Terminated.

IV. DETECTION

This exploit has been tested with the Dantz Retrospect Client version
7.0.107. This is the latest available on the vendor's website.

The version available for Mac is 6.0 has also been tested
and is not vulnerable to the issue described in this document.

V. WORKAROUND

iDefense is unaware of any workaround for this issue.

VI. VENDOR RESPONSE

"This problem has been resolved in the latest updates to the Retrospect
Client for Windows versions 7.0.109 and 6.5.138 software. All customers
who use the Retrospect Client Software versions 6.5 or 7 are encouraged
to download and install the latest Retrospect Client software, at no
additional cost, from the EMC Web site at:

  http://www.emcinsignia.com/supportupdates/updates/retrospect/archive/

Retrospect Express and Retrospect 7.5 customers do not need this
update."

The EMC KB article for this issue is found at:

  http://kb.dantz.com/article.asp?article=8361&p=2

VII. CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.

VIII. DISCLOSURE TIMELINE

12/15/2005  Initial vendor notification
12/15/2005  Initial vendor response
03/02/2006  Public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

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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.