Microsoft released software updates for versions of Windows XP and Windows Server 2003 and warned customers about a security vulnerability in a Windows component called IDirectPlay4, which is used to support multiplayer network games.

The security hole, if successfully exploited, could allow a remote attacker to cause a Windows application using the affected component to fail, creating a denial of service attack. Microsoft published a bulletin describing the hole, MS04-016, and rated the problem "moderate," indicating that the hole is difficult to exploit or can be fixed by changing configuration settings or other factors.

IDirectPlay4 is one of three APIs that make up Microsoft DirectPlay, a protocol that provides networking services for networks based on TCP/IP and IPX. DirectPlay is frequently used to support multi-player games.

A remote attacker could trigger the security vulnerability by connecting to a machine using DirectPlay and sending a specially misformatted data packet to the machine. When received, that packet would cause the application using DirectPlay to crash, Microsoft said.

Microsoft provided patches for both 32 and 64-bit versions of Windows XP and Windows Server 2003 and said customers should consider applying the updates.

The company also patched three of its products to plug a newly discovered hole in the Crystal Reports and Crystal Enterprise reporting tools from Business Objects SA. Software updates were released for Visual Studio .NET and Outlook 2003 with Business Contact Manager, which redistribute Crystal Reports. A patch was also issued for Microsoft Business Solutions CRM 1.2, which redistributes Crystal Enterprise and is also affected, Microsoft said.

The hole, if successfully exploited, could allow a remote attacker to use a Web interface to Crystal Reports and Crystal Enterprise to retrieve or delete files on affected systems, Microsoft said.

Microsoft published a bulletin concerning the hole, MS04-017, which rated the vulnerability "moderate". Customers should consider applying the patch, the company said.

Microsoft released the patches in keeping with its stated policy of trying to limit security updates to one day, typically the second Tuesday of each month.

After releasing more than 20 patches for security holes in April, many of them related to "critical" holes in versions of Windows and the Internet Explorer Web browser, the company has had two quiet months. The company issued one bulletin in April for a single, non-critical vulnerability.

However, yesterday, two previously unknown vulnerabilities in Internet Explorer were revealed which allow a malicious user to download software directly onto someone's hard disk. The exploits are in the wild and work on fully patched systems.