MS01-007: Patch Available for Network DDE Agent Request Vulnerability (285851)

SYMPTOMS

Microsoft has released a patch that eliminates a security vulnerability in Microsoft Windows 2000. The vulnerability could allow a malicious user to gain complete control over an affected computer.

Network Dynamic Data Exchange (DDE) is a technology that enables programs on different Windows-based computers to share data. This data sharing is accomplished by using communications channels that are called trusted shares, and trusted shares are managed by a service that is called the Network DDE Agent. By design, processes on the local computer can levy requests upon the Network DDE Agent, including ones that indicate what program should be run in conjunction with a particular trusted share. However, a vulnerability exists in Windows 2000 because the Network DDE Agent runs by using the Local System security context and processes all requests by using this context, rather than that of the user. This would give a malicious user an opportunity to cause the Network DDE Agent to run code in the Local System context. By doing so, a malicious user could gain complete control over the local computer.

To exploit this vulnerability, the malicious user would need the ability to run code on an affected computer. However, best practices strongly recommend against ever allowing unprivileged users to run code on security-critical computers such as domain controllers and other servers. If these recommendations have been followed, such computers would not be at risk. In addition, computers that are running Terminal Services are not affected by this vulnerability (except in the case where unprivileged users are allowed to log on at the console, which is never recommended). As a result of these limitations, workstations are most likely to be the computers that are affected by the vulnerability. Damage done by this vulnerability should be limited because, in most cases, even gaining complete control of a workstation would not convey any addition privileges on the domain.

Microsoft recommends that customers that are using Windows 2000-based workstations or who allow unprivileged users to run code on Windows 2000-based servers apply this patch immediately. As an additional precautionary measure, customers that are operating Windows 2000-based Web servers should consider applying the patch to those computers. If a malicious user were able to gain the ability to run code in a restricted context on a Web server by using another vulnerability, this vulnerability would provide a way to immediately elevate the malicious user's privileges and cause broader damage.

   Date        Time     Version        Size     File name
   --------------------------------------------------------
   5/29/2001   09:41a   5.0.2195.3649  178,960   Winlogon.exe