A new vulnerability in Java has been discovered.  The vulnerability allows an attacker to gain control of a victim’s computer. The researchers have confirmed that

  • Java SE 5 – Update 22 (Java SE 5 build 1.5.0_22-b03)
  • Java SE 6 – Update 35 (Java SE 6 build 1.6.0_35-b10 )
  • Java SE 7 Update 7 (Java SE 7 build 1.7.0_07-b10)

This vulnerability is caused by a discrepancy with how the Java virtual machine handles defined data types and in doing so violates a fundamental security constraint in the Java runtime, allowing a complete bypass of the Java sandbox.

The flaw allows the attacker to gain complete control of a victim’s machine through a malicious website.  Affected web browsers are

  • Safari 5.1.7
  • Opera 12.02
  • Chrome 21.0.1180.89
  • Firefox 15.0.1
  • Internet Explorer 9.0.8112.16421

Even with fully patched Windows 7 32-bit operating systems you are susceptible to the attack.

So far there are no reports of the flaw being used in any malware.  I would take a few preventative steps

  • Reducing the number of active runtimes (code execution environments) on your system
  • If you do not need Java uninstalling or disable it

Oracle released a fix for the most critical vulnerabilities on August 30.  The last exploit would allow an attacker to use a malicious Java applet to install programs, or read and change data on the system with the privileges of the current user.

But now another flaw in that fix allows a hacker to bypass the patch. That bug in Oracle’s patch still hasn’t been patched, leaving users vulnerable to both the new flaw and the previous attack.  It’s not yet known when or if Oracle will fix this issue.  Oracle has been provided with a technical overview of the bug and example code outlining the flaw but has not yet acted upon it.