We recently came across an attack campaign which looked quite unusual compared to the standard attacks normally seen in the wild. This campaign is targeting government agencies by sending phishing emails with a malicious attachment. Nothing new so far, except for one thing: the malicious payload is a Java remote access tool (RAT).
As we all know, cybercriminals tend to use recent hot media topics to entice users. In the case of this campaign they are using the recent news coverage surrounding the NSA surveillance program PRISM.
Figure 1. Phishing email example
The phishing email contains two legitimate non-malicious PDF documents and one Java file that mimics the name of a legitimate document. If a user is tricked into clicking this fake document, the Java applet will be run (providing that Java is installed on the user’s computer).
This applet is a RAT named jRat, it is available for free and Symantec detects it as Backdoor.Jeetrat. This threat can give full control of the compromised computer to a remote attacker. More importantly, because it is a Java applet the threat is able to run on multiple operating systems, not just Windows. In fact, the threat has a builder tool that allows you to build your own customized versions of the RAT, and we can see that when it comes to the targeted operating systems, the choice is very broad.
Figure 2. RAT builder control panel with options, including supported operating systems
The RAT can target not only Windows, but also Linux, Mac OSX, FreeBSD, OpenBSD, and Solaris (although we have not verified or observed the threat working on all of these operating systems). In principle, the threat may be able to run on any system that supports Java.
We searched our archives for other threats using the same command-and-control (C&C) server used in this specific attack and found an RTF document.
Figure 3. Malicious RTF document from previous attack campaign
This malicious RTF document exploits the Microsoft Windows Common Controls ActiveX Control Remote Code Execution Vulnerability (CVE-2012-0158), detected by Symantec as Bloodhound.Exploit.457. This shows that the same attackers were previously using the usual attack method of sending malicious documents that exploit some vulnerability in order to drop an executable payload but recently shifted to sending malicious Java payloads directly. The attack has been simplified as it does not involve the use of an exploit, nor an executable shellcode/payload, but simply relies on a Java applet. Nonetheless, it is no less dangerous than the older attacks and it can spread more easily since exploits are usually limited to work on specific versions of the vulnerable software and operating system, while this RAT can spread on any system where Java runtime is installed. In fact, not only has the attack been simplified, but it has also become more stable and more virulent, it is a big upgrade!
The distribution of this malware indicates most targets are located in the United States.
Figure 4. Malware distribution
Besides RATs, we have also seen other classes of Java malware being used in the wild. For more information about other uses of Java malware, check out this series of three blog entries about Java.Cogyeka.
In conclusion, while this new attack is a little unusual, it can be detected and blocked like older ones. We advise our customers to update their definitions and to be very cautious when receiving suspicious emails.