For those who haven't received the alert yet -----Original Message----- From: Microsoft [mailto:0_46534_0317731C-4DB0-46DD-8649-F9798862948C_US@xxxxxxxxxxxxxxxx osoft.com] Sent: Wednesday, April 09, 2003 3:25 PM To: David V. Dellanno Subject: Microsoft Security Bulletin MS03-012: Flaw In Winsock Proxy Service And ISA Server Firewall Service Can Cause Denial Of Service (331066) -----BEGIN PGP SIGNED MESSAGE----- - ------------------------------------------------------------------- Title: Flaw In Winsock Proxy Service And ISA Firewall Service Can Cause Denial Of Service (331066) Date: 09 April 2003 Software: Microsoft Proxy Server 2.0, Microsoft ISA Server Impact: denial of service Max Risk: Important Bulletin: MS03-012 Microsoft encourages customers to review the Security Bulletins at: http://www.microsoft.com/technet/security/bulletin/MS03-012.asp http://www.microsoft.com/security/security_bulletins/ms03-012.asp - ------------------------------------------------------------------- Issue: ====== There is a flaw in the Winsock Proxy service in Microsoft Proxy Server 2.0, and the Microsoft Firewall service in ISA Server 2000, that would allow an attacker on the internal network to send a specially crafted packet that would cause the server to stop responding to internal and external requests. Receipt of such a packet would cause CPU utilization on the server to reach 100%, and thus make the server unresponsive. The Winsock Proxy service and Microsoft Firewall service work with FTP, telnet, mail, news, Internet Relay Chat (IRC), or other client applications that are compatible with Windows Sockets (Winsock). These services allow these applications to perform as if they were directly connected to the Internet. These services redirect the necessary communications functions to a Proxy Server 2.0 or ISA Server computer, thus establishing a communication path from the internal application to the Internet through it. Mitigating Factors: ==================== - - The vulnerability would not enable an attacker to gain any privileges on an affected Proxy Server 2.0 or ISA Server computer or compromise any cached content. It is strictly a denial of service. - - ISA Server computers running in cache mode are not affected because the Microsoft Firewall service is disabled by default. Risk Rating: ============ Important Patch Availability: =================== A patch is available to fix this vulnerability. Please read the Security Bulletins at http://www.microsoft.com/technet/security/bulletin/ms03-012.asp http://www.microsoft.com/security/security_bulletins/ms03-12.asp for information on obtaining this patch. - ---------------------------------------------------------------- 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. 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