Microsoft yesterday warned of security flaws with DirectX's DirectShow component that might be used by an attacker to run hostile code on vulnerable Windows machines.

Redmond has issued a patch - designated as critical - which users are urged to review.

So too is Windows NT 4.0 with either Windows Media Player 6.4 or IE 6 SP 1 installed and Microsoft Windows NT 4.0, Terminal Server Edition with either Windows Media Player 6.4 or IE 6 SP 1 installed.

The DirectX APIs are used by Windows programs for multimedia and games support. Within DirectX, DirectShow performs client-side audio and video sourcing, manipulation, and rendering.

Two buffer overrun flaws in the function used by DirectShow to check parameters in a Musical Instrument Digital Interface (MIDI) file create a means to inject malicious code into vulnerable machines, hence the alert.

An attacker could seek to exploit this vulnerability by creating a specially crafted MIDI file designed to exploit this vulnerability and then host it on a Web site or on a network share, or send it by using an HTML-based e-mail. Simply visiting a maliciously constructed site might be enough to get infected, Microsoft warns. If the users open a maliciously constructed HTML email the effect will be the same.

Little wonder that Microsoft designates the problem as critical.

Microsoft's advisory, and links to patches, can be found here.

Credit for finding the problem goes to eEye Digital Security. ®