DOCUMENT:Q293826 15-AUG-2002 [iis] TITLE :Pattern-Matching Function Causes Access Violation on FTP Server PRODUCT :Internet Information Server PROD/VER::4.0,5.0 OPER/SYS: KEYWORDS:kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbgraphxlinkcritical KbSECVulnerabili ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Internet Information Services version 5.0 - Microsoft Internet Information Server version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== A denial of service (DoS) vulnerability exists in Microsoft Internet Information Services (IIS) 5.0 and Microsoft Internet Information Server (IIS) 4.0 because the function that processes wildcard sequences in FTP commands does not always allocate sufficient memory when it performs pattern matching. Under unusual circumstances, it may be possible for an attacker to levy an FTP command containing a wildcard sequence that, when expanded, can overrun the allocated memory and cause an access violation. This scenario can cause the IIS service (which provides both Web and FTP functionality) to fail. As a result, all Web or FTP sessions that are in progress at the time are severed, and no new sessions can be established until the IIS service is restarted. In IIS 5.0, the service restarts automatically. In IIS 4.0, operator intervention is required to restart the service. The attacker cannot add, change, or delete data on the server through this vulnerability, nor can the attacker usurp any administrative privileges. Mitigating Factor The attacker must be able to start an FTP session in order to exploit the vulnerability. CAUSE ===== This problem occurs because of a flaw in a pattern-matching function that is used by at least one FTP command. Depending on the wildcard sequence that is entered and the specific configuration of the server's file system, it is possible for the resulting pattern to exceed the available memory and trigger an access violation. This, in turn, causes the IIS service to fail. RESOLUTION ========== For additional information on what is fixed by the following patches, click the article number below to view the article in the Microsoft Knowledge Base: Q297860 IIS 5.0 Security and Post-Windows NT 4.0 SP5 IIS 4.0 Patch Rollup Internet Information Services 5.0 --------------------------------- 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 The English version of this fix should have the following file attributes or later: Date Time Version Size File name -------------------------------------------------------- 5/31/2001 03:31p 5.0.2195.3649 245,520 Adsiis.dll 5/31/2001 03:31p 5.0.2195.3649 332,560 Asp.dll 5/29/2001 04:37p 4.0.2.4701 593,976 Fp4autl.dll 5/31/2001 03:31p 5.0.2195.3649 246,032 Httpext.dll 5/31/2001 03:31p 5.0.2195.3649 56,592 Httpodbc.dll 5/31/2001 03:31p 5.0.2195.3649 122,640 Iisrtl.dll 5/31/2001 03:31p 5.0.2195.3649 13,584 Infoadmn.dll 5/31/2001 03:31p 5.0.2195.3649 245,520 Infocomm.dll 5/31/2001 03:31p 5.0.2195.3649 62,736 Isatq.dll 5/31/2001 03:31p 5.0.2195.3649 46,352 Ism.dll 5/31/2001 03:31p 5.0.2195.3649 76,560 Msw3prt.dll 5/30/2001 03:40p 5.0.2195.3651 6928 Schmupd.exe 5/30/2001 03:40p 5.0.2195.3651 7952 Spiisupd.exe 5/31/2001 03:32p 5.0.2195.3649 41,232 Ssinc.dll 5/31/2001 03:32p 5.0.2195.3649 7440 W3ctrs.dll 5/31/2001 03:32p 5.0.2195.3649 353,040 W3svc.dll Internet Information Server 4.0 ------------------------------- A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin (http://www.microsoft.com/technet/security/bulletin/ms01-026.asp) to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. To resolve this problem immediately, download the fix by clicking the download link later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, please visit the following Microsoft Web site: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The following file is available for download from the Microsoft Download Center: DownloadDownload Q295534i.exe now (http://www.microsoft.com/Downloads/Release.asp?ReleaseID=29787) NOTE: Q295534is.exe are the Symbols files. For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Q119591 How to Obtain Microsoft Support Files from Online Services Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on secure servers that prevent any unauthorized changes to the file. The English version of this fix should have the following file attributes or later: Date Time Version Size File name -------------------------------------------------------- 04/11/2001 01:32p 4.2.764.1 214,544 Adsiis.dll 04/11/2001 01:33p 4.2.764.1 330,672 Asp.dll 04/02/2001 04:55p 4.0.2.4701 593,976 Fp4autl.dll 04/11/2001 01:32p 4.2.764.1 81,888 Ftpsvc2.dll 04/11/2001 01:32p 4.2.764.1 55,392 Httpodbc.dll 04/11/2001 01:32p 4.2.764.1 98,912 Iischema.dll 04/11/2001 01:31p 4.2.764.1 63,472 Iislog.dll 04/11/2001 01:31p 4.2.764.1 185,792 Infocomm.dll 04/11/2001 01:31p 4.2.764.1 29,520 Iscomlog.dll 04/11/2001 01:35p 4.2.764.1 54,560 Ism.dll 04/02/2001 04:55p 4.0.1381.7086 375,056 Kernel32.dll 04/11/2001 01:36p 4.2.764.1 9,680 Schmupd.exe 04/11/2001 01:32p 4.2.764.1 38,256 Ssinc.dll 04/11/2001 01:32p 4.2.764.1 25,360 Sspifilt.dll 04/11/2001 01:32p 4.2.764.1 229,024 W3svc.dll 04/11/2001 01:31p 4.2.764.1 88,032 Wam.dll NOTE: You can install this patch on systems that are running Microsoft Windows NT 4.0 Service Pack 5 or Windows NT 4.0 Service Pack 6a. STATUS ====== Internet Information Services 5.0 --------------------------------- Microsoft has confirmed that this problem may cause a degree of security vulnerability in 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 Internet Information Server 4.0. MORE INFORMATION ================ 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 The 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 For more information on this vulnerability, see the following Microsoft Web site: http://www.microsoft.com/technet/security/ms01-026 Additional query words: security_patch kbWin2000srp1 ====================================================================== Keywords : kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbgraphxlinkcritical KbSECVulnerability KbSECHack KbSECDOS 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.