__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN VeriSign Managed PKI Configuration Checker [US-CERT Vulnerability Note VU#308087] February 22, 2007 18:00 GMT Number R-158 ______________________________________________________________________________ PROBLEM: The VeriSign Configuration Checker ActiveX control contains a stack buffer overflow, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system. PLATFORM: VeriSign DAMAGE: May allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system. SOLUTION: Upgrade to the appropriate version. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. May allow a remote, unauthenticated ASSESSMENT: attacker to execute arbitrary code on a vulnerable system. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/r-158.shtml ORIGINAL BULLETIN: http://www.kb.cert.org/vuls/id/308087 ______________________________________________________________________________ [***** Start US-CERT Vulnerability Note VU#308087 *****] Vulnerability Note VU#308087 VeriSign Managed PKI Configuration Checker ActiveX control stack buffer overflow Overview The VeriSign Configuration Checker ActiveX control contains a stack buffer overflow, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system. I. Description The VeriSign Configuration Checker ActiveX control is provided by web-based digital certificate enrollment sites and also by the VeriSign Managed PKI OnSiteMSI package. This control is vulnerable to a stack buffer overflow in the VerCompare() method, which can allow an overwrite of the process Structured Exception Handler (SEH). II. Impact By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code with the privileges of the user. The attacker could also cause Internet Explorer (or the program using the WebBrowser control) to crash. III. Solution Apply an update VeriSign Japan has published a page to check if the vulnerable ActiveX control is installed. If the vulnerable control is found, a download link to an update is provided. This update removes the VSCnfChk.dll file, which provides the vulnerable ActiveX control. Please note that this update will not prevent the vulnerable control from being installed again in the future. Therefore, we recommend the following workarounds: Disable the VeriSign Configuration Checker ActiveX control in Internet Explorer The vulnerable ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID: {08F04139-8DFC-11D2-80E9-006008B066EE} 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\ {08F04139-8DFC-11D2-80E9-006008B066EE}] "Compatibility Flags"=dword:00000400 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 Verisign Vulnerable 19-Feb-2007 References http://www.cert.org/tech_tips/securing_browser/#Internet_Explorer https://download.verisign.co.jp/support/announce/20070216.html https://download.verisign.co.jp/support/announce/20070216/check.html https://download.verisign.co.jp/support/announce/20070216/faq.html https://download.verisign.co.jp/support/announce/20070216/tool/mpki_vscnfchk_eu_ sp1_japanese.msi http://jvn.jp/cert/JVNVU%23308087/index.html http://support.microsoft.com/kb/240797 Credit This vulnerability was reported by VeriSign Japan. This document was written by Will Dormann and Chris Taschner. Other Information Date Public 02/16/2007 Date First Published 02/22/2007 11:09:29 AM Date Last Updated 02/22/2007 CERT Advisory CVE Name Metric 8.80 Document Revision 15 [***** End US-CERT Vulnerability Note VU#308087 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of US-CERT for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. 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