The Windows Media Player ASX (Active Stream Redirector) processor contains an unchecked buffer susceptible to an overrun which could enable an attacker to run arbitrary code on a machine with the victim's level of permission, a Microsoft security bulletin warns.

Media Player 6.4 and 7.0 are affected; and earlier, currently-unsupported versions 'may or may not be,' the company says.

Alternatively, a malicious HTML page could be set up to run an attack script automatically when it's viewed.

A second, less destructive, vulnerability could enable an attacker to exploit maliciously-crafted shortcuts, which Media Player 6.4 and 7.0 save to the user's temporary files directory with a known file name.

"It's possible for HTML code to be stored in such a shortcut and launched via a Web page or HTML e-mail, in which case the code would run in the Local Computer Zone rather than the Internet Zone. An attacker could exploit this vulnerability to read - but not add, delete or modify - files on another user's computer," the security bulletin explains.

Media Player 6.4 users can download a patch to clear up both defects here; while 7.0 users can fix their systems by upgrading to 7.1 here. ®