Bug Endures in Microsofts IE Patch

By Larry Seltzer  |  Posted 2004-02-04 Print this article Print

UPDATED: Anti-spoofing fix leaves status bar display bug unrectified. Issue is minor since the browser won't take the user to the false site.

A patch Microsoft Corp. released on Monday for a dangerous Internet Explorer vulnerability that lets attackers trick Internet users into visiting malicious sites doesnt completely fix the problem. The cumulative patch addresses, among other problems, a display bug likely to be used by phishing attacks. If the attacker uses a particular malformed URL syntax, only a portion of the actual address would appear in the address bar, creating the opportunity for the attacker to give a false impression of the site being visited.

The MS04-004 patch addresses this bug, but not a related problem. If the user visits a Web page containing such a malformed link and hovers the mouse over the link or selects it by tabbing through links in the page, the patched version of Internet Explorer will display the partial URL in the status bar.

For example, take the link: "www.paypal.com%00%01@security.eweek.com." On an unpatched copy of Internet Explorer, clicking the link will open a new window and bring the browser to security.eweek.com, the eWEEK.com Security Topic Center. On a patched copy of IE the browser will go to an error page indicating illegal syntax. Still, on either version of IE, if you hover over the link on this page, the status bar will display www.paypal.com.

Ironically, the cumulative patch also fixed another bug in a different IE cumulative update from last year. That cumulative patch addressed several security issues in Internet Explorer, but also introduced bugs in the behavior of the IE scrollbar. The new patch fixes these bugs.

Editors Note: This story was updated to remove an example of a malformed link. The code caused some antivirus software and patched versions of IE to report illegal coding.
Larry Seltzer has been writing software for and English about computers ever since—,much to his own amazement—,he graduated from the University of Pennsylvania in 1983.

He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find absolutely no hits on any of these +products on Google.) His work at Desktop Software included programming the UCSD p-System, a virtual machine-based operating system with portable binaries that pre-dated Java by more than 10 years.

For several years, he wrote corporate software for Mathematica Policy Research (they're still in business!) and Chase Econometrics (not so lucky) before being forcibly thrown into the consulting market. He bummed around the Philadelphia consulting and contract-programming scenes for a year or two before taking a job at NSTL (National Software Testing Labs) developing product tests and managing contract testing for the computer industry, governments and publication.

In 1991 Larry moved to Massachusetts to become Technical Director of PC Week Labs (now eWeek Labs). He moved within Ziff Davis to New York in 1994 to run testing at Windows Sources. In 1995, he became Technical Director for Internet product testing at PC Magazine and stayed there till 1998.

Since then, he has been writing for numerous other publications, including Fortune Small Business, Windows 2000 Magazine (now Windows and .NET Magazine), ZDNet and Sam Whitmore's Media Survey.

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