Aza Raskin of Mozilla has developed a new type of phishing attack that takes advantage of the way that browsers handle tabbed browsing. The attack could be used for highly targeted attacks against customers of a specific bank, Webmail service or credit-card company. When the user visits the site, the attacker s code detects which other tabs the user has open in her browser and checks to see which ones haven t been visited in a while. The JavaScript code then changes the favicon of that tab and the content on the page to look like whatever the attacker chooses.
Source: https://threatpost.com/new-tabbed-browsing-phishing-attack-exploits-user-trust-052510/74011/