RSnake at ha.ckers.org raises concerns about the information being sent by the phone home feature of Google safebrowsing software built into Mozilla Firefox and Google Chrome browsers. "I noticed two additional pieces of information that were being phoned home outside of Safe Browsing. This time, instead of it being 30 times an hour, it was more like once every 5 hours, which is still quite a bit if you ask me.
The two extra pieces of data were “machineid” and “userid” – both computed information based on machine/user information. This information is sent along with a bunch of other browser information to ask Google if they should download an update. Now here’s the real question: why would Google need to know my machineid and userid to give me an update – wouldn’t the version number of my browser be enough to make that decision? I just can’t believe this isn’t used for tracking. There’s no more plausible deniability. What a perfect way to spy on people too… use their own browser against them in the name of security." – Content courtesy of Google Safe-Browsing and Chrome Privacy Leak ha.ckers.org web application security lab