Flaw In Winsock Proxy Service And ISA Firewall New

A flaw exists 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.

Issue

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.

Affected Products

• Microsoft Proxy Server 2.0
• Microsoft ISA Server

Download

Software patches are available from the following locations:

• Microsoft Proxy Server 2.0
• Microsoft ISA Server

Further Details

Source: Microsoft Corporation

Reference: Microsoft Corporation

Updated: April 9, 2003

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