The good news is that the download is not triggered just by surfing to a website offering the ads, but the bad news is that there are plenty of people out there that look at US green cards as a ticket to a good life, and are likely to click on the them.
Doing so triggers a pop up saying that the user is using an outdated version of Firefox and that a browser update is recommender in order to view the wanted page.
According to ThreatTrack's analysis, the website is capable of detecting which browser the user uses and to recommend an update for it.
Nevertheless, the offered "update" is always the same: Firefox v13 (long outdated - the current version is 23), with several "add-ons, adware, toolbars and other malicious and irritating accompaniments" also trying to get installed via the installation wizard:
Among this tag-along software is the Delta Toolbar, Webcake (a browser add-on that, among other things, serves ads), Optimizer Pro (a questionable PC-tune-up program), QuickShare (a deceptive browser plugin that steals data and redirects to unwanted websites) and an ad for “unlimited cloud storage”.
All this "crapware" is sure to bring grief to the victims. It will slow down their computer, for sure, but the biggest problem is that they will end up with a outdated browser that can be successfully targeted with drive-by-download schemes, more additional malware and they will likely become victims of identity theft in the long run.
So, be careful what you click on and what you download from the Internet, and be always wary of unsolicited download offers, however urgent and necessary they are made to sound.