Apparently there are security flaws in the current version of Java allowing the installation of malicious software through web browsers unknown to the user. The known attacks using this flaw work on Windows, OSX, and Linux. According to Reuters:
Java was responsible for 50 percent of all cyber attacks last year in which hackers broke into computers by exploiting software bugs, according to Kaspersky. That was followed by Adobe Reader, which was involved in 28 percent of all incidents. Microsoft Windows and Internet Explorer were involved in about 3 percent of incidents, according to the survey.
The Department of Homeland Security recently said computer users should disable Java. At first this seems odd. The vulnerability in question is only in Java 7. So why not go back to Java 6? Well, Java 6 has vulnerabilities too, which is why DHS and others have recommended getting to 7. Also, starting in 7, the automatic upgrades are more aggressive. So going backwards is probably not a great idea. (If just happens I had to go backwards to get a tool I needed to work and forgot to go back forward.)
Also, for a similar situation back in August the recommendation was to make the browser prompt before allowing Java to run. The strategy is just stop Java entirely. Apple has removed Java browser plugins. That could work too. Except for bad, bad software like ours (sorry, sarcasm if you could not tell) which makes use of a few applets. In the last week I have gotten a request to add another applet.
A fix to Java 7′s vulnerabilties should be available in a couple days.