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AUSCERT External Security Bulletin Redistribution
ESB-2008.0883 -- [Win]
InstallShield / Macrovision / Acresso FLEXnet Connect
insecurely retrieves and executes scripts
24 September 2008
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AusCERT Security Bulletin Summary
---------------------------------
Product: InstallShield / Macrovision / Acresso FLEXnet Connect
Publisher: US-CERT
Operating System: Windows
Impact: Execute Arbitrary Code/Commands
Access: Remote/Unauthenticated
CVE Names: CVE-2008-1093
Original Bulletin: http://www.kb.cert.org/vuls/id/837092
Revision History: September 24 2008: Added CVE Name
September 17 2008: Initial Release
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Vulnerability Note VU#837092
InstallShield / Macrovision / Acresso FLEXnet Connect insecurely retrieves
and executes scripts
Overview
Acresso FLEXnet Connect executes scripts that are insecurely retrieved
from a remote web server, which can allow a remote, unauthenticated
attacker to execute arbitrary code on a vulnerable system.
I. Description
Acresso FLEXnet Connect is a software package that allows vendors to
provide updates to applications. FLEXnet Connect-enabled software has the
ability to
* Check for updates from the software publisher
* Receive update files and messages from the software publisher
* Install software updates, including the ability to do so silently
* Collect and transmit system information, such as machine name,
operating system, IP address, or other hardware details, such as
network or video card properties
* Log and transmit each time an application is started, terminated, or
when a specific feature within the application is used
Acresso FLEXnet Connect was formerly known as Macrovision FLEXnet Connect,
and before that it was known as InstallShield Update Service.
The FLEXnet Connect client software communicates with centralized servers to
check for updates and other product information on a periodic basis. Updates
can also be triggered by using Internet Explorer to visit a web page that
uses the FLEXnet Connect ActiveX control, which is provided by agent.exe.
When connecting to the server, the client can receive special instructions
(rules) to assist in evaluating whether an update is relevant. These
instructions are provided by a GetRules.asp page on a web server. These
rules are presented in a scripting language, such as VBScript.
FLEXnet Connect retrieves rules insecurely in that it uses unsigned and
unencrypted communication using the HTTP protocol, which can allow an
attacker to inject code that will be executed on the client system. This
can happen in a number of ways, including
1. Compromising the FLEXnet Connect servers directly.
2. Filtering client system traffic through a malicious proxy.
3. Compromising DNS servers or otherwise modifying the host name lookup
methodology of a client system.
Depending on how the vendor has configured the FLEXnet Connect components,
the check for updates may occur on a periodic basis, every time an
application is launched, when a user checks for updates manually, or if a
web page that uses the FLEXnet ActiveX control is visited. Any software
that has been packaged with the vulnerable InstallShield, Macrovision, or
Acresso components may be vulnerable.
II. Impact
By modifying the rule script that is sent to a FLEXnet Connect client, a
remote unauthenticated attacker may be able to execute arbitrary code on a
vulnerable system.
III. Solution
We are currently unaware of a practical solution to this problem. Please
consider the following workarounds:
Restrict access to GetRules.asp
Enterprises that have proxy capabilities could disable access to the
GetRules.asp URLs that are used to download the script instructions,
however this may have consequences to programs that depend on the rules
for determining patch applicability.
Disable the DWUpdateService ActiveX control in Internet Explorer
The vulnerable ActiveX control can be disabled in Internet Explorer by
setting the kill bit for the following CLSIDs:
{551E5190-19C7-4626-9D54-FB20355E6467}
{8D9BB053-FEE5-4411-B6F5-F1E37DDC3106}
{EE4E49B0-38EC-4C23-A7A6-2E190B5E3418}
{FFF2D28F-E4EE-44D9-8104-8E71556757F6}
More information about how to set the kill bit is available in Microsoft
Support Document 240797. Alternatively, the following text can be saved
as a .REG file and imported to set the kill bit for this control:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{551E5190-19C7-4626-9D54-FB20355E6467}]
"Compatibility Flags"=dword:00000400
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{8D9BB053-FEE5-4411-B6F5-F1E37DDC3106}]
"Compatibility Flags"=dword:00000400
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{EE4E49B0-38EC-4C23-A7A6-2E190B5E3418}]
"Compatibility Flags"=dword:00000400
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{FFF2D28F-E4EE-44D9-8104-8E71556757F6}]
"Compatibility Flags"=dword:00000400
Note that this list of CLSIDs may not be complete. Different versions of
FLEXnet Connect or InstallShield Update Service use different CLSIDs for
the ActiveX control that can be used to trigger updates.
Restrict access to the FLEXnet Conect client components
The vulnerable update components can be disabled by restricting access to
the ISSCH.EXE and ISUSPM.EXE components on Microsoft Windows Systems. These
executable files are for the InstallShield Update Service Scheduler and the
Macrovision FLEXnet Connect Update Manager, respectively. These programs
are used to periodically check for software updates using FLEXnet Connect.
Users may also wish to rename the
"\Program Files\Common Files\InstallShield\UpdateService" or related
UpdateManager folders of other products to prevent automated execution of
these programs until a fix is provided. Note that this may interfere with a
product's ability to retrieve updates, including security fixes.
Disable ActiveX
Disabling ActiveX controls in the Internet Zone (or any zone used by an
attacker) appears to prevent exploitation of this and other ActiveX
vulnerabilities. Instructions for disabling ActiveX in the Internet Zone
can be found in the "Securing Your Web Browser" document.
Systems Affected
Vendor Status Date Updated
Acresso Vulnerable 16-Sep-2008
Corel Corporation Vulnerable 16-Sep-2008
InstallShield Vulnerable 16-Sep-2008
Intel Corporation Not Vulnerable 16-Sep-2008
Macrovision Vulnerable 15-Sep-2008
Roxio Vulnerable 16-Sep-2008
References
http://www.simplicity.net/vuln/CVE-2008-1093.txt
Credit
Thanks to Brian Dowling of Simplicity Communications for reporting this
vulnerability.
This document was written by Will Dormann.
Other Information
Date Public 16/09/2008
Date First Published 16/09/2008 13:48:11
Date Last Updated 16/09/2008
CERT Advisory
CVE-ID(s) CVE-2008-1093
NVD-ID(s) CVE-2008-1093
US-CERT Technical Alerts
Metric 9.90
Document Revision 28
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