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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. |
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Credit:
The information has been provided by iDefense.
The original article can be found at:
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=479
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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
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