ISA Server H.323 Gatekeeper Service Contains Memory Leak New

A security vulnerability exists in the Internet Security and Acceleration (ISA) Server Gatekeeper service and Winsock Proxy service which could allow a remote malicious user to cause a denial of service attack by exploiting a memory leak.

Issue

The Gatekeeper service in ISA Server allows for sophisticated call handling and routing of H.323 Voice over IP (VoIP) calls; the Winsock Proxy service allows internal users to gain access to Internet resources. Malformed packets that are directed at the services can cause the H323asn1.dll dynamic-link library (DLL) to consume system resources and not release them.

There is no memory leak if the Gatekeeper service is not started. The Gatekeeper service loads the H323asn1.dll DLL when it starts. Resources are handled typically if you have not configured your H.323 gateway, and such an attack would have no effect.

Affected Products

• Microsoft ISA Server 2000

Download

Patch: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=32094

Further Details

Source: Microsoft Corporation

Reference: Microsoft Corporation

Updated: August 16, 2001

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