The beta version of Internet Explorer 9 released by Microsoft this week comes with at least one significant security enhancement -- the Download Manager scans files for malware and issues warnings when it detects malicious code.

Microsoft has integrated the Download Manager with its SmartScreen URL filter, a feature that first debuted in IE 8. SmartScreen is an anti-phishing and anti-malware filter that blocks badware in real-time, based on Microsoft's application reputation database. In IE 9, the browser's Download Manager now also blocks downloads from known malicious URLs: It flashes a warning in the browser's new notification bar as well as in Download Manager. The user then decides whether to download it.

The new download reputation feature also helps eliminate false positives for known and safe files, according to Microsoft. It issues a severe warning when the file attempting to download is at high risk of being malicious. "Users today are often conditioned to ignore generic warnings that are shown for every download. Other browsers show the same warning whether a file is an extremely common program or a piece of malware created literally minutes ago. Internet Explorer 9 is the only browser that uses download reputation to help users make safety decisions," Microsoft's website for IE 9 says.

The downside of user alerts popping up elsewhere and not at the top of the page is that this could cause some confusion, noted one security expert who requested anonymity. "Unfortunately, this could cause problems where users are confused about what they're clicking on, or even click on the wrong thing, depending on the situation," the expert says.

But, overall, the new IE appears to have stronger built-in security than previous versions, experts say. "[IE 9] deals with security more intelligently than prior versions. And security, visual capability, and performance are three of the key areas the product is designed to excel in," says Rob Enderle, principal analyst, The Enderle Group. "On security, they have increased its ability to look for unusual downloads and flag them, identify known hostile sites more rapidly, and while the plug-in identification tool is designed for speed, it will also help users identify plug-ins they may have already installed that are doing bad things."

The new browser also has randomized memory management, which makes hacking it more difficult, he says. Other new features include a limit on redirection, which makes it harder to hijack a user to a malicious site. New protections for cross-site scripting and clickjacking are also part of this release, as well as a new protection mode akin to Google's sandboxing mode for Chrome, Enderle says. This lets "a user who knows they might be going someplace dangerous to effectively raise shields that will better protect them," he says.

IE 9 beta is available for download here.

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