iDEFENSE Security Advisory 06.23.05: Veritas Backup Exec Agent Error Status Remote DoS Vulnerability
Veritas Backup Exec Agent Error Status Remote DoS Vulnerability
iDEFENSE Security Advisory 06.23.05
www.idefense.com/application/poi/display?id=271&type=vulnerabilities
June 23, 2005
I. BACKGROUND
VERITAS Backup Exec is an advanced backup and restore solution for
Microsoft Windows server environments. More information is available
from the vendor's website:
http://veritas.com/Products/www?c=product&refId=57
II. DESCRIPTION
Exploitation of a buffer overflow vulnerability in Veritas Software
Corp.'s Backup Exec allows remote attackers to execute arbitrary code.
The Veritas Backup Exec Agent listens on TCP port 10000 and is
responsible for accepting connections from the backup server when a
backup is to occur. Typically the agent would be installed on most
servers and important workstations in an enterprise environment.
Veritas Backup Exec uses the standard NMDP protocol to communicate with
the listening agents.
The vulnerability specifically exists because of improper handling of
request packets with an unexpected "Error Status" value. Specifically,
any Error Status other than "0" will cause a null pointer dereference,
resulting in an unhandled exception as can be seen as follows.
eax=00000000 ebx=0032ac08 ecx=00000000
edx=0098a930 esi=0032e1e8 edi=009b5770
eip=008f1c84 esp=00fbfb58 ebp=0032ac30 iopl=0
nv up ei pl nz na pe nc
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010202
*** ERROR: Symbol file could not be found.
Defaulted to export symbols for
C:\Program Files\VERITAS\Backup Exec\NT\ndmpsrvr.dll -
ndmpsrvr+0x21c84:
008f1c84 8b00 mov eax,[eax] ds:0023:00000000=????????
The unhandled exception will result in a crash of the program and a
denial of service condition.
III. ANALYSIS
Exploitation does not require authentication, thereby allowing any
remote attacker to cause the denial of service and disruption of backup
capabilities.
IV. DETECTION
iDEFENSE has confirmed the existence of this vulnerability in Backup
Exec for Windows Servers versions 9.0, 9.1 and 10.0. It is suspected
that other versions are also vulnerable.
Several vendors ship or use Veritas software including Hitachi and NEC
Corporation.
V. WORKAROUND
Use a firewall to restrict incoming connections to trusted workstations
running the Backup Exec client software which uses port 10000 TCP.
VI. VENDOR RESPONSE
The vendor has addressed this vulnerability in security advisories
VX05-001 and VX05-008:
http://seer.support.veritas.com/docs/276533.htm
http://seer.support.veritas.com/docs/277485.htm
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-0772 to this issue. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
03/16/2005 Initial vendor notification
03/30/2005 Initial vendor response
06/22/2005 Coordinated public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
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X. LEGAL NOTICES
Copyright (c) 2005 iDEFENSE, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
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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.