Severity: Medium
7 March 2008
Summary:
- These vulnerabilities affect: All versions of Sun Java Runtime Environment (JRE) released before 4 March, on Windows, Solaris, and Linux platforms
- How an attacker exploits them: By enticing your users to a malicious web page that contains a specially crafted Java applet or application
- Impact: Various results; in the worst case, attacker can gain complete control of your computer
- What to do: Install the appropriate JRE update as soon as possible
Severity: Medium
7 March 2008
Summary:
- These vulnerabilities affect: All versions of Sun Java Runtime Environment (JRE) released before 4 March, on Windows, Solaris, and Linux platforms
- How an attacker exploits them: By enticing your users to a malicious web page that contains a specially crafted Java applet or application
- Impact: Various results; in the worst case, attacker can gain complete control of your computer
- What to do: Install the appropriate JRE update as soon as possible
Exposure:
Java is a programming language (first implemented by Sun Microsystems) used most often to add neat features to Web pages. Most operating systems today implement a Java interpreter to recognize and process Java code from Web sites and other sources. Sun’s Java Runtime Environment (JRE) is one of the most popular Java interpreters currently used on the Internet.
Yesterday, US-CERT released a security alert warning of multiple vulnerabilities that affect all previous versions of Sun JRE (as well as Sun Java SDK) running on Windows, Solaris and Linux platforms. While the vulnerabilities differ quite a bit technically, an attacker can exploit them all in a similar manner. If an attacker can entice one of your users to download a malicious Java applet or application from a web page or HTML e-mail, he can exploit these vulnerabilities in a variety of ways. He can cause JRE to crash, to access local files on your user’s hard drive, or to execute local applications on your user’s PC. In the worst case, the attacker could even execute arbitrary code of his own choosing. And if your users have local administrative privileges, the attacker could potentially exploit some of these flaws to gain complete control of your users’ machines.
If you run a Solaris or Linux network, you probably know whether or not you use Sun JRE (in most cases, you do). If you manage a Windows network, however, your answer is less clear. In the past, Windows shipped with Microsoft’s own Java interpreter, called Java Virtual Machine (MSJVM); since these editions of IE use MSJVM to interpret Java applets, most Windows users who browse with IE aren’t vulnerable to this flaw. Because of a legal conflict with Sun, though, Microsoft had to discontinue the use of MSJVM in its most recent versions of Windows. For instance, MSJVM doesn’t ship with Windows Server 2003 or the Windows XP installer that comes with prepackaged SP1a or SP2 (XP users who upgraded to SP1 or SP2 on their own retain MSJVM). These newer Windows releases require that you download your own Java interpreter; in which case, you probably do have Sun JRE and need to update as soon as possible.
If you’re unsure what your version of IE uses to interpret Java, there’s an easy way to find out. In IE, click on Tools => Internet Options => Advanced tab. Scroll down to the Microsoft VM section and check “Java console enabled.” Restart IE and then click View => Java Console. A window opens which displays the name and version number of the Java interpreter your IE browser uses. If you’re not using Sun JRE, the vulnerability doesn’t affect you.
Solution Path:
Sun has released various JRE and SDK updates to correct these issues. If you use Sun JRE in your network, download and deploy the corresponding updates as soon as possible:
- JRE and JDK 6.0: Download JRE or JDK 6.0 Update 5
- JRE and JDK 5.0: Download JRE or JDK 5.0 Update 15
- JRE and SDK 1.4.x: Download JRE or SDK 1.4.2_17
- JRE and SDK 1.3.x: Download JRE or SDK 1.3.1_22
For All WatchGuard Users:
Some of WatchGuard’s Firebox models allow you to prevent your users from downloading Java applets from Web sites. Doing so, however, also cripples legitimate Web sites using Java applets. If you do not want to block Java applets, download the appropriate Sun JRE updates as soon as possible.
To learn how to use your Firebox’s HTTP proxy to block Java applets, see the “Deny Java Applets” section of the HTTP Proxy Advanced FAQ.
Status:
Sun has issued updates to correct these issues.