A flaw in Sun Microsystems’ plug-in for running Java on a variety of browsers and operating systems could allow a virus to spread through Microsoft Windows and Linux PCs.

The vulnerability, found by Finnish security researcher Jouko Pynnonen in June, was patched last month by Sun, but its details were not made public until Tuesday. Security information provider Secunia posted information about the flaw in an advisory that rated it a “highly critical” threat.

The Java plug-in enables small Web programs, known as applets, to run safely on a user’s computer. But the security flaw allows a malicious Web site accessed through a victim’s browser to bypass those protections.

“It allows execution of attacker-supplied code without user interaction (apart from viewing a Web page) which usually means a ‘critical’ classification”

“The same exploit could also be used against various operating systems and browsers, which makes it more serious,” he added. The vulnerability can be used to attack systems running on Windows or Linux, for example, and using major browser software such as Microsoft’s Internet Explorer and Firefox–meaning a large number of systems are vulnerable to attack.

An attacker could use the flaw to do anything the victim normally could, including browse, modify or run files, upload more programs to the victim’s system, or send out data from the system, Pynnonen wrote in an advisory dated Tuesday.

While Sun would not speculate on how the flaw could be used by attackers, the company did say that it worked hard to distribute the patch for it to all users.

Source: News.com