Computer Associates BrightStor ARCserve Backup UniversalAgent Buffer 
Overflow

iDEFENSE Security Advisory 04.11.05
www.idefense.com/application/poi/display?id=232&type=vulnerabilities
April 11, 2005

I. BACKGROUND

BrightStor ARCserve Backup provides backup and restore protection for 
all classes of Windows, NetWare, Linux and UNIX servers, as well as 
Windows, Mac OS X, Linux, UNIX, AS/400 and VMS client environments.

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in Computer 
Associates International Inc's BrightStor ARCserve Backup UniversalAgent

may allow attackers to execute arbitrary code.

The BrightStor software uses a network agent to perform backups on nodes

across the network. This agent service requires either administrative 
credentials or a node-specific password and is capable of backing up 
system settings as well as files. This agent will listen on TCP and UDP 
ports 6050 by default.

When an agent request is received on the TCP port, with the "option" 
field set to 0, 3 or 1000, and a large string preceding this "option"
field in the packet, an overflow will occur. The agent software
includes its own exception handler, preventing the service from
actually crashing. Each time an exception occurs due to this overflow,
the handler will kick in and restore the service back to an operating
state. This particular overflow will cause three exceptions, two of
which are non-exploitable, and one which can be used to hijack
execution.

III. ANALYSIS

Successful exploitation of this vulnerability allows for a remote 
unauthenticated compromise with system level access. Although 
exploitation of this vulnerability is not trivial, it has been shown 
that it can be done reliably.

IV. DETECTION

Computer Associates BrightStor ARCserve Backup v11 (Win32) has been 
confirmed vulnerable.

V. WORKAROUND

Employ firewalls, access control lists or other TCP/UDP restriction 
mechanism to limit access to systems and services.

VI. VENDOR RESPONSE

Vendor advisories and patches for this vulnerability are available at:

BrightStor ARCserve Backup r11.1 for Windows (all components):
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66526&
startsearch=1

BrightStor ARCserve Backup r11.1 Client Agent for Windows only:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66527&
startsearch=1

BrightStor ARCserve Backup r11.1 for Windows - 64 bit edition:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66534&
startsearch=1

BrightStor ARCserve Backup r11.0 for Windows:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66525&
startsearch=1

BrightStor ARCserve Backup r11.0 for Windows - 64 bit edition:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66535&
startsearch=1

BrightStor ARCserve Backup v9.01 for Windows English (all components):
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66528&
startsearch=1

BrightStor ARCserve Backup v9.01 for Windows Non-English (all
components):
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66529&
startsearch=1

BrightStor ARCserve Backup v9.01 for Windows - 64 bit edition:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66536&
startsearch=1

BrightStor ARCserve Backup v9.01 Client Agent for Windows only
(English):
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66530&
startsearch=1

BrightStor ARCserve Backup v9.01 Client Agent for Windows only
(Non-English):
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66531&
startsearch=1

BrightStor Enterprise Backup v10.5 for Windows:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66524&
startsearch=1

BrightStor Enterprise Backup v10.5 for Windows - 64 bit edition:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66533&
startsearch=1

BrightStor Enterprise Backup v10.0 for Windows:
http://supportconnect.ca.com/sc/solcenter/solresults.jsp?aparno=QO66523&
startsearch=1 

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1018 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

12/02/2004 Initial vendor notification
12/02/2004 Initial vendor response
04/11/2005 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
email customerservice@idefense.com for permission.

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.