From secnotif@MICROSOFT.COM Wed Mar 14 18:59:07 2001 From: Microsoft Product Security To: BUGTRAQ@SECURITYFOCUS.COM Date: Tue, 13 Mar 2001 19:21:22 -0800 Subject: [BUGTRAQ] Microsoft Security Bulletin MS01-016 (version 2.0) The following is a Security Bulletin from the Microsoft Product Security Notification Service. Please do not reply to this message, as it was sent from an unattended mailbox. ******************************** -----BEGIN PGP SIGNED MESSAGE----- - -------------------------------------------------------------------- Title: Malformed WebDAV Request Can Cause IIS to Exhaust CPU Resources Released: 08 March 2001 Revised: 13 March 2001 (version 2.0) Software: IIS 5.0 Impact: Denial of Service Bulletin: MS01-0016 Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS01-016.asp - -------------------------------------------------------------------- Reason for Revision: ==================== The original version of this bulletin provided a workaround (discussed in Knowledge Base article Q241520) that would protect affected systems by disabling WebDAV services. However, a security patch is now available that eliminates the vulnerability, and Microsoft recommends using the patch rather than the workaround. We have updated both the bulletin and the narrative below to reflect this. Issue: ====== WebDAV is an extension to the HTTP protocol that allows remote authoring and management of web content. In the Windows 2000 implementation of the protocol, IIS 5.0 performs initial processing of all WebDAV requests, then forwards the appropriate commands to the WebDAV process. However, a flaw exists in the way WebDAV handles a particular type of malformed request. If a stream of such requests were directed at an affected server, it would consume all CPU availability on the server. The patch should be applied to all machines running IIS 5.0. While this obviously includes web servers, it's worth noting that IIS 5.0 may be running on other types of servers as well, particularly mail servers running Exchange 2000. Mitigating Factors: ==================== - The effect of an attack via this vulnerability would be temporary. The server would automatically resume normal service as soon as the malformed requests stopped arriving. - The vulnerability does not provide an attacker with any capability to carry out WebDAV requests. - The vulnerability does not provide any capability to compromise data on the server or gain administrative control over it. Patch Availability: =================== - A patch is available to fix this vulnerability. Please read the Security Bulletin http://www.microsoft.com/technet/security/bulletin/ms01-016.asp for information on obtaining this patch. - ------------------------------------------------------------------- -----BEGIN PGP SIGNATURE----- Version: PGP Personal Privacy 6.5.3 iQEVAwUBOq7jso0ZSRQxA/UrAQF1QwgAlgv97QgEKhq/VR39SSQTzq4nEgvj0XFy jWrxuIwFlOKiIVFV61Tjjip7HSex1OgZF4UD1EafPeNcNmE+A157Ufk3/QeQXzxO dY0AF/cvSlGvBOk52Pw/RgYPbpez8/dAzgabz7vyDDm6zL1gqX7SKqNnzPEnldzy 8gB17X5KMduRdDSqTW7Rf09lFd9covzSZNGIDLnfzjBQiuA9UilgxxaDarfBrf67 lZ1oTjmdH1MRC39ki/p8ye0T5LSMT3AIRVCLFaJmqtOLoBV5bCIMpc1DtJhJJNqq t3uCTi0fCcWLxLvGucix+/a0INxJtF2CZCxPoPkn6yHB92rwYBgQ4w== =YUwQ -----END PGP SIGNATURE----- ******************************************************************* You have received this e-mail bulletin as a result of your registration to the Microsoft Product Security Notification Service. You may unsubscribe from this e-mail notification service at any time by sending an e-mail to MICROSOFT_SECURITY-SIGNOFF-REQUEST@ANNOUNCE.MICROSOFT.COM The subject line and message body are not used in processing the request, and can be anything you like. To verify the digital signature on this bulletin, please download our PGP key at http://www.microsoft.com/technet/security/notify.asp. For more information on the Microsoft Security Notification Service please visit http://www.microsoft.com/technet/security/notify.asp. For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security.