-----BEGIN PGP SIGNED MESSAGE----- CERT Advisory CA-2001-13 Buffer Overflow In IIS Indexing Service DLL Original release date: June 19, 2001 Last revised: -- Source: CERT/CC A complete revision history is at the end of this file. Systems Affected * Systems running Microsoft Windows NT 4.0 with IIS 4.0 or IIS 5.0 enabled * Systems running Microsoft Windows 2000 (Professional, Server, Advanced Server, Datacenter Server) * Systems running beta versions of Microsoft Windows XP Overview A vulnerability exists in the Indexing Services used by Microsoft IIS 4.0 and IIS 5.0 running on Windows NT, Windows 2000, and beta versions of Windows XP. This vulnerability allows a remote intruder to run arbitrary code on the victim machine. Since specific technical details on how to create an exploit are publicly available for this vulnerability, system administrators should apply fixes or workarounds on affected systems as soon as possible. I. Description There is a remotely exploitable buffer overflow in one of the ISAPI extensions installed with most versions of IIS 4.0 and 5.0 (The specific Internet/Indexing Service Application Programming Interface extension is IDQ.DLL). An intruder exploiting this vulnerability may be able to execute arbitrary code in the Local System security context. This essentially can give the attacker complete control of the victim system. This vulnerability was discovered by eEye Digital Security. Microsoft has released the following bulletin regarding this issue: http://www.microsoft.com/technet/security/bulletin/MS01-033.asp Affected versions of Windows include Windows NT 4.0 (installed with IIS 4.0 and Index Server 2.0), Windows 2000 (Server and Professional with IIS 5.0 installed), and Windows 2000 Datacenter Server OEM distributions; however, not all of these instances are vulnerable by default. The beta versions of Windows XP are vulnerable by default. The only precondition for exploiting this vulnerability is that an IIS server is running with script mappings for Internet Data Administration (.ida) and Internet Data Query (.idq) files. The Indexing Services do not need to be running. As stated by Microsoft in MS01-033: The buffer overrun occurs before any indexing functionality is requested. As a result, even though idq.dll is a component of Index Server/Indexing Service, the service would not need to be running in order for an attacker to exploit the vulnerability. As long as the script mapping for .idq or .ida files were present, and the attacker were able to establish a web session, he could exploit the vulnerability. This vulnerability has been assigned the identifier CAN-2001-0500 by the Common Vulnerabilities and Exposures (CVE) group: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0500 II. Impact Anyone who can reach a vulnerable web server can execute arbitrary code in the Local System security context. This results in the intruder gaining complete control of the system. Note that this may be significantly more serious than a simple "web defacement." III. Solution Apply a patch from your vendor Apply patches for vulnerable Windows NT 4.0 and Windows 2000 systems: For Windows NT 4.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30833 For Windows 2000 Professional, Server, and Advanced Server: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30800 These patches supersede the ones previously provided in Microsoft Security Bulletins MS01-025 and MS00-006. Users of Windows 2000 Datacenter Server software should contact their original equipment manufacturer (OEM) for patches. A list of OEM providers may be found here: http://www.microsoft.com/windows2000/datacenter/howtobuy/purchasing/oems.asp Workarounds Users of beta copies of Windows XP should upgrade to a newer version of the software when it becomes available. All affected versions of IIS/Indexing Services can be protected against exploits of this vulnerability by removing script mappings for for Internet Data Administration (.ida) and Internet Data Query (.idq) files. However, such mappings may be recreated when installing other related software components. Appendix A. Vendor Information Microsoft Corporation The following documents regarding this vulnerability are available from Microsoft: http://www.microsoft.com/technet/security/bulletin/MS01-033.asp References 1. VU#952336: Microsoft Index Server/Indexing Service used by IIS 4.0/5.0 contains unchecked buffer used when encoding double-byte characters CERT/CC, 06/19/2001, https://www.kb.cert.org/vuls/id/952336 2. Additional advice on securing IIS web servers is available from http://www.microsoft.com/technet/security/iis5chk.asp http://www.microsoft.com/technet/security/tools.asp Feedback concerning this document may be directed to Jeffrey S. Havrilla. ______________________________________________________________________ This document is available from: http://www.cert.org/advisories/CA-2001-13.html ______________________________________________________________________ CERT/CC Contact Information Email: cert@cert.org Phone: +1 412-268-7090 (24-hour hotline) Fax: +1 412-268-6989 Postal address: CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 U.S.A. CERT personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends. Using encryption We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from http://www.cert.org/CERT_PGP.key If you prefer to use DES, please call the CERT hotline for more information. Getting security information CERT publications and other security information are available from our web site http://www.cert.org/ To subscribe to the CERT mailing list for advisories and bulletins, send email to majordomo@cert.org. Please include in the body of your message subscribe cert-advisory * "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office. ______________________________________________________________________ NO WARRANTY Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement. _________________________________________________________________ Conditions for use, disclaimers, and sponsorship information Copyright 2001 Carnegie Mellon University. Revision History Jun 19, 2001: Initial Release -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 5.0i for non-commercial use Charset: noconv iQCVAwUBOy/WPwYcfu8gsZJZAQFG0wP/XxlOT28SV0ia3MSUMzJYLvCCMIypVNkg HITIX0PlKzshJusMYWcVZtgLe5PzhKNs4kk9qsJ8trVqkg5tevVVE4M7GP3VaZsf ioqXSRkoy+7LD3KTiUot13sYbnA4ggHYiwNfM/FqKsyB1g6+ihPLluXPjKWclx0Y WGOUkK1BHIk= =cqDS -----END PGP SIGNATURE-----