Many anti-virus products — particularly the “Internet security suite” variety — now ship with various Web browser toolbars, plug-ins and add-ons designed to help protect the customer’s personal information and to detect malicious Web sites. Unfortunately, if designed poorly, these browser extras can actually lower the security posture of the user’s system by introducing safety and stability issues.
The last time I caught up with security researcher Alex Holden, he was showing me a nifty way to crash IE6 and prevent the user from easily reopening the badly outdated and insecure browser version ever again. Just the other day, Holden asked me to verify a crash he’d found that affects users who have Trend Micro Internet Security installed, which installs a security toolbar in both Internet Explorer and Mozilla-based browsers on Microsoft Windows.
The video here was made on a virgin install of Windows XP SP3, with the latest Firefox build and a brand new copy of Trend Micro Internet Security. Paste a really long URL into the address bar with the Trend toolbar enabled, and Firefox crashes every time. Do the same with the toolbar disabled, and the browser lets the Web site at whatever domain name you put in front of the garbage characters handle the bogus request as it should. This isn’t limited to Firefox: The same long URL crashes IE8 with the Trend toolbar enabled, although for some strange reason it fails to crash IE6. I didn’t attempt to test it against IE7.