[NT] VeriSign ConfigChk ActiveX Control Buffer Overflow Vulnerability

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VeriSign ConfigChk ActiveX Control Buffer Overflow Vulnerability
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SUMMARY

The ConfigChk ActiveX Control is part of VeriSign Inc.'s MPKI, Secure
Messaging for Microsoft Exchange and Go Secure! products. It looks for the
Microsoft Enhanced Cryptographic Provider in order to support 1024-bit
cryptography.

Remote exploitation of a buffer overflow vulnerability in VeriSign Inc.'s
ConfigChk ActiveX Control could allow an attacker to execute arbitrary
code within the security context of the victim.

DETAILS

Vulnerable Systems:
* VeriSign Inc's VSCnfChk.dll version 2.0.0.2.
* (All versions are suspected to be vulnerable)

The ActiveX control in question, identified by CLSID
08F04139-8DFC-11D2-80E9-006008B066EE, is marked as being safe for
scripting.

The vulnerability specifically exists when processing lengthy parameters
passed to the VerCompare() method. If either of the two parameters passed
to this method are longer than 28 bytes, stack memory corruption will
occur. This amounts to a trivially exploitable stack-based buffer
overflow.

Successful exploitation of this vulnerability would allow a remote
attacker to execute arbitrary code within the context of the victim.

In order to exploit this vulnerability, an attacker would need to persuade
the victim into viewing a malicious web site. This is usually accomplished
by getting the victim into clicking a link in a form of electronic
communication such as e-mail or instant messaging.

Workaround:
Setting the kill-bit for this control will prevent exploitation of this
vulnerability through Internet Explorer.

Vendor Status:
VeriSign has addressed this vulnerability by releasing a patch which
corrects the security issues found in the affected .dll file.

Disclosure Timeline:
* 12/22/2006 - Initial vendor notification
* 12/20/2006 - Initial vendor response
* 02/22/2007 - Coordinated public disclosure


ADDITIONAL INFORMATION

The information has been provided by iDefense.
The original article can be found at:

<http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=479>
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=479



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