November 18, 2013, 2:04 PM — Attackers are actively exploiting a known vulnerability to compromise JBoss Java EE application servers that expose the HTTP Invoker service to the Internet in an insecure manner.
At the beginning of October security researcher Andrea Micalizzi released an exploit for a vulnerability he identified in products from multiple vendors including Hewlett-Packard, McAfee, Symantec and IBM that use 4.x and 5.x versions of JBoss. That vulnerability, tracked as CVE-2013-4810, allows unauthenticated attackers to install an arbitrary application on JBoss deployments that expose the EJBInvokerServlet or JMXInvokerServlet.
Micalizzi's exploit installs a Web shell application called pwn.jsp that can be used to execute shell commands on the operating system via HTTP requests. The commands are executed with the privileges of the OS user running JBoss, which in the case of some JBoss deployments can be a high privileged, administrative user.
Researchers from security firm Imperva have recently detected an increase in attacks against JBoss servers that used Micalizzi's exploit to install the original pwn.jsp shell, but also a more complex Web shell called JspSpy.
Over 200 sites running on JBoss servers, including some that belong to governments and universities have been hacked and infected with these Web shell applications, said Barry Shteiman, director of security strategy at Imperva.
The problem is actually bigger because the vulnerability described by Micalizzi stems from insecure default configurations that leave JBoss management interfaces and invokers exposed to unauthenticated attacks, a issue that has been known for years.
In a 2011 presentation about the multiple ways in which unsecured JBoss installations can be attacked, security researchers from Matasano Security estimated, based on a Google search for certain strings, that there were around 7,300 potentially vulnerable servers.
According to Shteiman, the number of JBoss servers with management interfaces exposed to the Internet has more than tripled since then, reaching over 23,000.
One reason for this increase is probably that people have not fully understood the risks associated with this issue when it was discussed in the past and continue to deploy insecure JBoss installations, Shteiman said. Also, some vendors ship products with insecure JBoss configurations, like the products vulnerable to Micalizzi's exploit, he said.