Critical Java updates fix 19 vulnerabilities, disable SSL 3.0

The updates were part of Oracle's quarterly Critical Patch Update, released Tuesday, which fixes 169 security issues across hundreds of products.

Fourteen of the 19 vulnerabilities fixed in Java affect client deployments and can be exploited from Web pages through malicious Java applets or Java Web Start applications. Four of them have the maximum severity score 10 in the Common Vulnerability Scoring System (CVSS) and two others come close, at 9.3, meaning they can lead to a full system compromise.

"The threats associated with sandbox bypass vulnerabilities in this CPU [Oracle Critical Patch Update] range from reading and writing local data to complete 'operating system takeover including arbitrary code execution'," said John Matthew Holt, the CTO of Java application security firm Waratek, via email. "Complete OS takeover vulnerabilities are the worst possible kind because attackers can use these vulnerabilities to not just steal sensitive or confidential data, but to install malware, steal passwords, assume a user's identity, delete files, and use the compromised machine as a pivot point to launch deeper attacks to other lateral machines within the same local area network."

The number of attacks that exploit Java vulnerabilities to install malware on computers has been on a steady decline over the past year, but Java exploits remain one of the top attack vectors against Web users, according to a report released Tuesday by Cisco Systems.

Another security-related change in the new Java updates is the deactivation of the SSL 3.0 protocol by default in response to the POODLE vulnerability discovered in October. The flaw allows man-in-the-middle attackers to decrypt sensitive information like authentication cookies from a connection encrypted with SSL 3.0.

What makes POODLE particularly dangerous is that even if a connection uses TLS 1.0, 1.1 or 1.2, an attacker can force a downgrade to SSL 3.0 if both the client and server support the aging protocol.

The change in Java comes as major browser vendors are taking similar actions in regard to support for SSL 3.0.

"If SSLv3 is absolutely required, the protocol can be reactivated by removing 'SSLv3' from the jdk.tls.disabledAlgorithms property in the java.security file or by dynamically setting this Security property to 'true' before JSSE is initialized," Oracle said in the new Java release notes.

The newly patched Java versions are 5.0u81, 6u91, 7u75/7u76 and 8u31, but the Java 5 and 6 updates are only available to Oracle customers with long term support contracts.

This is also the last public security update for Java 7. Users who have the automatic update feature turned on will be migrated to Java 8. Only users with long term support contracts will be able to download future Java 7 security fixes.