TrojanDownloader:Java/OpenConnection.PK

TrojanDownloader:Java/OpenConnection.PK is the detection for a Java based malware family that exploits a vulnerability discussed in CVE-2010-0840. The vulnerability affects Java Runtime Environment (JRE) up to and including version 6 release 18, and makes it possible for untrusted code to gain browser security privileges under the user's account.

A user may encounter a threat from this family when visiting a compromised website. If the user is using a vulnerable version of Java, successful exploitation resulting in infection can occur. To prevent reinfection, and avoid similar exploits, make sure up to date security patches are applied to the Java Runtime Environment. You can read more about this in the Recovery section below.

A number of legitimate websites could be compromised or unwillingly host a malicious applet through advertising frames which could redirect to or host a malicious Java applet. It is common for this detection to trigger in your Internet cache. When using Internet Explorer, the Internet cache is known as the Temporary Internet Files folder and is commonly located at C:\Users\<user name>\AppData\Local\Microsoft\Windows\Temporary Internet Files\. The Temporary Internet Files (or cache) folder contains webpage content that is stored on your hard disk for quick viewing. This cache permits Internet Explorer to download only the content that has changed since you last viewed a webpage, instead of downloading all the content for a page every time it is displayed.

When antivirus software to detects malicious Java applets in a web browser's cache, it doesn’t necessarily mean that the computer has been compromised. Most of the time it reflects the fact that, at some stage, a webpage with a malicious applet had been visited and cached internally. To thwart such a notification it is often enough to purge the cache using a web browser's configurable security options.

Installation

TrojanDownloader:Java/OpenConnection.PK is a collection of Java classes which exploit the CVE-2010-0840 vulnerability. The collection resides inside a JAR file and is referenced by a Java applet. The applet class will normally have some obscure class names and will be located inside a JAR package. An examples of a name we have seen used in the wild is "idmer.class".

TrojanDownloader:Java/OpenConnection.PK has been known to be bundled in the JAR package with another file detected as Exploit:Java/CVE-2010-0840.OG.

The applet reads a parameter which it expects to be specified in referencing the applet HTML file, and uses it as a location for a file to be downloaded and executed. The file is executed with elevated privileges.

Analysis by Wei Li