Only 59 percent of people use fully patched web browsers, putting the remainder at risk from growing threats from hackers, according to a study by Swiss researchers.
The study is one of the most comprehensive analyses of what versions of web browsers people are using on the Internet. The study was conducted by researchers at The Swiss Federal Institute of Technology, Google and IBM Internet Security Services.
Web browsers are often a weak link in the security chain, as software vulnerabilities can make it easy for hackers to gain control of a PC. When that happens, hackers can perform malicious acts such as stealing personal data or turning PCs into spam-spewing drones.
What the researchers found is that although software vendors provide patches for security problems, it can take days, weeks or months before people update their applications. In the meantime, those users are at risk.
But it's not entirely the fault of users, since web browser vendors haven't exactly made patching easy, said Stefan Frei, a doctoral student at the institute, which is known as ETH Zurich, and one of the report's authors. The web browser is still fairly young technology, and the industry has yet to settle on a dominant, well-tested design, he said.
The study looked at search and web application server log data provided by Google to see what versions of the Firefox, Opera or Safari browsers people were using, Frei said.
Microsoft's Internet Explorer, however, only tells web servers what major version a person is using, such as IE 6 or IE 7. The researchers relied on data from people who have installed a tool on their PC called the Personal Software Inspector, from Danish security company Secunia, that can detect incremental versions of IE, Frei said.
Firefox users were the best at upgrading: 83.3 percent are using the latest version (the study just looked at Firefox 2.0). For Apple's Safari, 65.3 percent use the latest version; 56.1 percent for Opera and 47.6 percent for Microsoft's Internet Explorer.
Mozilla's Firefox came out on top due to its auto-update feature, which tells a user a new patch is available and offers a one-click way to upgrade. Within three days, most Firefox users are up to date, the study said.
Frei recommends that all browser makers put in an auto-update feature since the process now is cumbersome and slow.
The problem with lax patching falls squarely on the shoulders of the application vendors - users often simply can't visually tell if their browser needs to be upgraded, Frei said.
He advocates software vendors take a cue from the food industry and put an "expiration date" right on top of the browser to let people know the browser's state. For example, a warning could appear beside the address bar: "145 days expired, three patches missing"
But the problem of out-of-date browsers pales in comparison to the quagmire of plug-ins, which add extra functionality to the browser, such as Adobe's Flash and Apple's QuickTime multimedia program.
On average, people have between six to 10 plug-ins, many of which come from different vendors with different patching regimes and schedules, Frei said.
The study will be presented at the Defcon security conference next month in Las Vegas.