is a family of malicious Java applets that try to exploit a vulnerability in the Java Runtime Environment (JRE) to download and install files of a hacker's choice onto your PC. Oracle Java SE JDK and JRE 7 and 6 Update 27 and earlier are all vulnerable to this exploit.
To check if you're running a vulnerable version of Java:
- Go to the control panel (Select Start|Control Panel)
- Select Programs. If Java is installed you will see it in the list of installed programs. Click it to open the Java Control Panel.
- On the General tab, click About to see which version of Java you have installed.
Make sure that you install all available updates from the vendor to avoid this exploit. You can read more about this vulnerability and download software updates from these links:
Note: This detection may be triggered when you visit a website that contains the malicious code. Even if you are not using a vulnerable version of the JRE this detection may be reported when you visit a website that contains the malicious code. This does not mean that you have been compromised, rather that someone has tried to infect your PC.
Threat in context
Java is a general-purpose programming language, but cases of this exploit are targeted against the Java plug-in for web browsers. The intent of the Java plug-in is that Java programs (or "applets") can be offered by websites, and run in a "sandbox" where the Java plug-in enforces rules on what the Java applet can do so that it cannot escape outside the webpage it is included in.
What is an exploit?
Exploits are written to take advantage of weaknesses (or "vulnerabilities") in legitimate software. A project called "Common Vulnerabilities and Exposures" (or "CVE"), used by many vendors and organizations, gives each vulnerability a unique number, in this case "CVE-2011-3544". The portion "2011" refers to the year the vulnerability was discovered, and "3544" is a unique ID for this specific vulnerability. The official source that gives out CVE identifiers lists this at http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-3544.
Downloads and installs files
If you visit a website containing the malicious code while using a vulnerable version of Java, Exploit:Java/CVE-2011-3544 is loaded. It then tries to download and run files from a remote host/URL. The files that are downloaded and run could be any of the hacker's choice and could include additional malware.
Additional technical details
In summary, Exploit:Java/CVE-2011-3544 attacks the security model instead of a buffer overflow. With a buffer overflow, the exploit is dependent on the specific CPU (Central Processing Unit), and might be affected by technology like DEP (Data Execution Prevention) or ASLR (Address Space Layout Randomization).
Attacking the security model means that the exploit might be effective on any platform the Java interpreter is on; for example Windows, MacOS, Linux, etc.
Usually the exploits are written using a few Java classes working together. The various class files are bundled into an archive called a JAR, which uses the ZIP file format. Every JAR contains a Manifest.MF file to identify itself to the Java Runtime. Since it is found in every JAR, it won't be listed.
Below are some examples of files that exploit the vulnerability described in CVE-2011-3544:
00237384c62d1e260f6ed9a277f80bdd37cc3a61, 029bb2d8f3bc7cf79cd249798b69d3410efee6a0, 033d594bcaa585db419f76aeaca0edd74c8e02aa
00c12fd7e080575de56869f66e4d8a973ca96f74, 023683cb65ff1a7779d0d66427fa8ce5f21d65c4, 026298551b026211c2533274c02f060438eb6107
Some payloads are specifically targeted against MacOS X, for example:
(a configuration file for the payload)
Once the exploit obtains full privileges on your PC, it may:
- Run a file (that may be detected as malware) included in the JAR
- Run a file from (that may be detected as malware) a URL hardcoded in the exploit's file
- Take instructions from the HTML file (like a URL to the malware file) that loaded them
In the wild, we have observed the following malware being distributed in the exploit's JAR files:
Related information / Related references
The articles referenced below outline some of the the technical details of the weakness this vulnerability exploits:
Analysis by Chris Stubbs