Client Fingerprinting via Analysis of Browser Scripting Environment
property in that it has date/time characteristics which are helpful in identifying the browser. Firefox 2.0.0.x uses the YYYYMMDDHH format, while Firefox 3+ uses the YYYYMMDD format. Although the resolution on the navigator.productSub is not very granular, it may not allow individual O/S variants to be identified it will most likely allow the version of Firefox to be identified.
There are two basic ways in which to customize Firefox to pretend to be a different browser; setting the ‘general.useragent.extra.firefox’ property within about:config or using a browser extension like User Agent Switcher.