__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Internet Security and Acceleration (ISA) Server Error Pages Could Allow Cross-Site Scripting Attack [Microsoft Security Bulletin MS03-028] July 17, 2003 21:00 GMT Number N-119 ______________________________________________________________________________ PROBLEM: A cross-site scripting vulnerability exists in many of the error pages that are returned by the ISA server under specific error conditions. PLATFORM: Microsoft ISA Server 2000 DAMAGE: The vulnerability would allow an attacker who operated a Web site and was able to lure another user into clicking a link on it to carry out a cross-site scripting attack via another Web site that was running through ISA Server. This would enable the attacker to run script in the user's browser using the security settings of the other Web site, and to access cookies and other data belonging to it. SOLUTION: Apply patch as stated in Microsoft's security bulletin. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. To exploit this flaw, an attacker would ASSESSMENT: have to first be aware of a specific ISA server and its access policies or host an ISA server of their own and create specific access policies designed to exploit this vulnerability. The attacker would have to create a specially-formed HTML e-mail and send it to the user, host a Web site that contained a Web page used to exploit this vulnerability, and persuade a user to visit that site. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-119.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/ default.asp?url=/technet/security/bulletin/MS03-028.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS03-028 *****] Microsoft Security Bulletin MS03-028 Flaw in ISA Server Error Pages Could Allow Cross-Site Scripting Attack (816456) Originally posted: July 16, 2003 Summary Who should read this bulletin: System administrators running Microsoft® Internet Security and Acceleration (ISA) Server 2000 Impact of vulnerability: Allows an attacker to execute code of their choice Maximum Severity Rating: Important Recommendation: System administrators should install the patch at the earliest available opportunity. End User Bulletin: An end user version of this bulletin is available at: http://www.microsoft.com/security/security_bulletins/ms03-028.asp. Affected Software: * Microsoft Internet Security and Acceleration (ISA) Server 2000 Technical details Technical description: ISA Server contains a number of HTML-based error pages that allow the server to respond to a client requesting a Web resource with a customized error. A cross-site scripting vulnerability exists in many of these error pages that are returned by ISA Server under specific error conditions. To exploit this flaw, an attacker would have to first be aware of a specific ISA server and its access policies or host an ISA server of their own and create specific access policies designed to exploit this vulnerability. The attacker could then craft a request to trigger a page refusal. Once the attack was crafted, the attacker would have to host a Web site containing the link, or send the link to the user in the form of an HTML e-mail. After the user previewed or opened the e-mail, the malicious site could be visited automatically without further user interaction. In the Web-based attack scenario, an attacker would have no way to force a user to visit the Web site. Mitigating factors: * The vulnerability could only be exploited if the attacker could entice another user into visiting a Web page, or opening an HTML-based e-mail. * The request must be one that would cause the ISA server to respond with one of several affected error pages. * The vulnerability would not normally enable an attacker to gain any privileges on an affected ISA Server computer, breach the firewall, or compromise any cached content, unless the user is operating on the ISA server itself and is using the Web Proxy service to access the Internet. Severity Rating: ISA Server Important The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. Vulnerability identifier: CAN-2003-0526 Tested Versions: Microsoft tested ISA Server to assess whether it is affected by this vulnerability. Previous versions are no longer supported, and may or may not be affected by this vulnerability. Patch availability Download locations for this patch * Microsoft ISA Server: English French German Spanish Japanese Additional information about this patch Installation platforms: This patch can be installed on systems running Microsoft ISA Server Service Pack 1 and Microsoft ISA Server with Feature Pack 1 installed. Inclusion in future service packs: The fix for this issue will be included in the next ISA Server service pack. Reboot needed: No. Patch can be uninstalled: Yes. Superseded patches: None. Verifying patch installation: * To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fpc\Hotfixes\SP1\277 * To verify the individual files, use the date/time and version information provided in Knowledge Base article 816456 Caveats: None Localization: Localized versions of this patch are available at the locations discussed in “Patch Availability”. Obtaining other security patches: Patches for other security issues are available from the following locations: * Security patches are available from the Microsoft Download Center, and can be most easily found by doing a keyword search for "security_patch". * Patches for consumer platforms are available from the WindowsUpdate web site Other information: Acknowledgments Microsoft thanks Brett Moore of Security-Assessment.com for reporting this issue to us and working with us to protect customers. Support: * Microsoft Knowledge Base article 816456 discusses this issue and will be available approximately 24 hours after the release of this bulletin. Knowledge Base articles can be found on the Microsoft Online Support web site. * Technical support is available from Microsoft Product Support Services. There is no charge for support calls associated with security patches. Security Resources: The Microsoft TechNet Security Web Site provides additional information about security in Microsoft products. Disclaimer: The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions: * V1.0 (July 16, 2003): Bulletin Created. * V1.1 (July 16, 2003): Clarified mitigating factor. [***** End Microsoft Security Bulletin MS03-028 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft Corporation 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. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) N-109: Microsoft Flaw in ISAPI Extension for Windows Media Services Could Cause Code Execution N-110: Red Hat Updated XFree86 Packages Provide Security and Bug Fixes N-111: Red Hat Updated unzip Packages Fix Trojan Vulnerability N-112: Red Hat Updated PHP Packages Fix Bugs N-113: Sun Buffer Overflow in LDAP Name Service N-114: Buffer Overrun in Microsoft HTML Converter Could Allow Code Execution N-115: Buffer Overrun in Microsoft Windows Could Lead to Data Corruption N-116: Flaw in Microsoft Windows Message Handling through Utility Manager Could Enable Privilege Elevation N-117: Microsoft RPC Interface Buffer Overrun Vulnerability N-118: Cisco IOS Interface Blocked by IPv4 Packet