Browsers leave a certain amount of finger print. i.e. Flash version, Java and the browser versions and type is pretty easy to obtain. This may be enough inform

Browsers leave a certain amount of finger print. i.e. Flash version, Java and the browser versions and type is pretty easy to obtain. This may be enough information to produce a targeted attack. They also used timing attacks against various localhost ports using XMLHttpRequest. This is enough to detect Avast, Avira, ESET, Kaspersky, and Trend Micro antivirus products