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EMC Legato Networker nsrexecd.exe Heap Overflow Vulnerability

01.17.06

BACKGROUND

EMC Legato NetWorker is a cross-platform backup and recovery
application.

DESCRIPTION

Remote exploitation of a heap overflow vulnerability in EMC Corp.'s
Legato Networker allows attackers to execute arbitary code on windows
platforms.

The vulnerability specifically exists due to improper handling of
malformed RPC requests to RPC program number 390113. When such a request
is sent by an attacker, it is possible to overwrite portions of heap
memory, thus leading to arbitrary code execution by way of a function
pointer overwrite. If an attacker can populate memory so that his data
is in a predictable location, arbitrary code execution is possible. It
is possible to populate memory in several ways, including by utilizing
memory leaks.

ANALYSIS

Successful exploitation allows a remote attacker to gain access to a
targetted machine. As nsrd.exe is installed on backup client machines
as well as server machines, an attacker may rapidly compromise a
network using this vulnerability.

DETECTION

iDefense has confirmed this vulnerability in Networker 7.2 build 172.
All previous versions are suspected vulnerable.

WORKAROUND

iDefense is currently unaware of any workarounds for this issue.

VENDOR RESPONSE

"Complete resolutions to the vulnerabilities are available today in
NetWorker 7.1.4 and 7.3.  EMC has created a hot-fix to protect against
vulnerabilities for 7.2.1 customers.  No fixes are planned for previous
NetWorker releases."

"These remedies are available for download at:"

http://www.legato.com/support/websupport/product_alerts/011606_NW.htm

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-3658 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

DISCLOSURE TIMELINE

11/17/2005 Initial vendor notification
11/17/2005 Initial vendor response
01/17/2006 Coordinated public disclosure

CREDIT

Jo Goossens is credited with the discovery of this vulnerability.

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LEGAL NOTICES

Copyright © 2006 Verisign, Inc.

Permission is granted for the redistribution of this alert
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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.