DOCUMENT:Q319688 15-AUG-2002 [iis] TITLE :MS02-018: Patch Available for Chunked Encoding Vulnerability PRODUCT :Internet Information Server PROD/VER::4.0,5.0 OPER/SYS: KEYWORDS:kbenv kbSecurity kbCOMIS kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbWin2000sp3fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Internet Information Services version 5.0 - Microsoft Internet Information Server version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== A buffer overrun vulnerability exists in Internet Information Server (IIS) 4.0 and Internet Information Services (IIS) 5.0. By sending a specially chosen request to an affected web server, an attacker could either disrupt Web services or gain the ability to run a program on the server. Such a program would run with full system privileges in IIS 4.0, and with fewer but nevertheless significant privileges in IIS 5.0. Customers who have used the IIS Lockdown Tool to configure their servers as static Web servers are already protected against this vulnerability. Likewise, the URLScan tool can be configured to block the vulnerability, and the affected mechanism itself can be disabled. However, because of the seriousness of the vulnerability, Microsoft recommends that all customers install the patch, including those who have already taken these steps. CAUSE ===== This vulnerability results because of an arithmetic error in the Active Server Pages (ASP) functionality that enables data to be uploaded to a Web server by using chunked encoding. The error causes IIS to allocate a buffer of the wrong size to hold incoming data, with the result that the data could overrun the end of the buffer and neighboring system memory. RESOLUTION ========== - Internet Information Services 5.0 - Internet Information Server 4.0 Internet Information Services 5.0 --------------------------------- The update for this problem is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base: Q319733 MS02-018: April 2002 Cumulative Patch for Internet Information Services To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: Q260910 How to Obtain the Latest Windows 2000 Service Pack Internet Information Server 4.0 ------------------------------- The update for this problem is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base: Q319733 MS02-018: April 2002 Cumulative Patch for Internet Information Services STATUS ====== Internet Information Services 5.0 --------------------------------- Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Internet Information Services 5.0. This problem was first corrected in Windows 2000 Service Pack 3. Internet Information Server 4.0 ------------------------------- Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Internet Information Server 4.0. MORE INFORMATION ================ The vulnerability that is described in this article does not apply to Internet Information Services (IIS) 5.1. However, a variant of this vulnerability that affects IIS 4.0, 5.0, and 5.1 exists elsewhere in the chunked-encoding mechanism. This variant could be exploited in a similar manner as the preceding vulnerability, and would have the same scope. The update for these vulnerabilities is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base: Q319733 MS02-018: April 2002 Cumulative Patch for Internet Information Services For more information about these vulnerabilities, see the following Microsoft Web site: http://www.microsoft.com/technet/security/bulletin/MS02-018.asp For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base: Q265173 Datacenter Program and Windows 2000 Datacenter Server Product For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base: Q296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot Additional query words: kbIISCom security_patch kbIIS400500510April2002Rollup ====================================================================== Keywords : kbenv kbSecurity kbCOMIS kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbWin2000sp3fix Technology : kbiisSearch kbiis500 kbiis400 Version : :4.0,5.0 Hardware : x86 Issue type : kbbug Solution Type : kbfix ============================================================================= 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. Copyright Microsoft Corporation 2002.