Microsoft announced two new moderate-risk security holes that affect Windows NT and Windows 2000 late Thursday and offered patches to fix both.
The more serious of the two holes affects most versions of Windows NT and 2000, including server versions, and could allow an attacker to elevate privileges or run code on a local machine, according to Microsoft.
The vulnerability affects the Multiple Uniform Naming Convention Provider (MUP) service on these systems, which helps them to identify the location of network resources, Microsoft said. When MUP requests a file using the Uniform Naming Convention, two buffers are created and a buffer overflow vulnerability exists in the second, the Redmond, Washington, company said. An attacker could overrun this buffer, causing a system crash or allowing code of the attacker's choice to be run, Microsoft said.
The flaw is mitigated because MUP requests can only be launched locally by a user logged on to the local machine and because the attack cannot be used to reliably run code on Windows 2000 systems, the company said.
More information about the flaw, and the patch to repair it, are available at http://www.microsoft.com/technet/security/bulletin/ms02-017.asp. The second vulnerability affects Windows 2000 Server products and can allow an attacker to block the application of Group Policy. It is a moderate-risk flaw, according to Microsoft.
The security hole affects the way Group Policies are applied to users logging on to a Windows 2000 Server. An attacker could log on to a network twice, locking the read-only Group Policy files with the first log on, thus making the second log on free from those policies and subject only to the most recent policies, Microsoft said. This attack could cause the policy change to affect not only the attacker, but also anyone else who logged on while the Group Policy files were locked, the company said.
The vulnerability is mitigated by a number of factors, including that an attacker would have to already possess a legitimate username and password for the system and that the attacker could not change Group Policy.
More information about the flaw, and the patch to repair it, are available at http://www.microsoft.com/technet/security/bulletin/ms02-016.asp