Be careful. Playing some streaming music or video files could allow hackers to entertain themselves with your system. A nefarious code jockey could commandeer your computer by causing Windows Media Player versions 6.4 and 7 to malfunction. The malicious code would be embedded not in the streaming file itself but in an Active Stream Redirector (.asx) file that tells Windows Media Player where to find the streaming media file.

In the worst-case scenario, the perpetrator would gain the ability to do anything on your PC that you could do--such as deleting or renaming files and even reformatting your hard disk. All you'd have to do to set the chain of events in motion would be to visit the site where the bogus file was located--you wouldn't even have to play the file. Alternatively, the attacker could send you the .asx file and entice you to preview or play it. If you saved it to your hard disk and then clicked on it, the hacker would have free rein with your system.

A second Windows Media Player bug offers attackers a different avenue through which to infiltrate your computer. This flaw affects your system only if you use an add-on skin--an alternative user interface that alters Media Player's look and feel.

Microsoft has posted a patch that fixes both vulnerabilities. Find it and the lowdown on the bugs in this Security Bulletin.

Keep Snoops Away From Your Data

Microsoft has been busier fixing potholes in Internet Explorer than a highway construction crew patching the ruts in Pottstown, Pennsylvania, during the rainy season.

If you use Internet Explorer 5.5 (the latest version), you're vulnerable to a glitch that could turn your PC into a hacker's playground. IE 5.5 has a new feature called Print Templates (used in IE's Print Preview mode) that enables you to customize how Web pages look when you print them out. Bug sleuth Warren Greer discovered a flaw in the Print Templates design that could permit an application on a hacker's Web site to execute its own Print Template remotely on your computer, with potentially disastrous results. Suppose that you unknowingly visit a hacker's site. As soon as you click the print icon on the diabolical site's custom template, the site offers you its own Print Template to use. Code hidden in this template could exploit IE 5.5's design flaw to let the hacker change data in your files, or to send data to another computer via the Internet.

Microsoft has issued a patch that fixes the Print Template bug and a handful of other snafus. To apply the fix, though, your system must have IE 5.5, IE 5.5 Service Pack 1, or IE 5.01 Service Pack 1. Get the skinny on the bugs and the patch.