[BreachExchange] Samsam Server-Side Ransomware Targets K-12 Schools, Hospitals

[Inga Goddijn]

http://www.eweek.com/security/samsam-server-side-ransomware-targets-k12-schools-hospitals.html

Criminals have started targeting hospitals and schools with ransomware,
using vulnerabilities in popular application servers to infiltrate
organizations' networks and to insert backdoors to allow access, according
to an analysis by networking giant Cisco.

In a scan of the Internet, the company found that more than 3.2 million
computers <http://blog.talosintel.com/2016/04/jboss-backdoor.html> running
the popular JBoss application server are likely at risk of being attacked.
Already, some 2,100 servers hosted at 1,600 Internet addresses show signs
of being infected by a testing and exploitation tool known as JexBoss,
which enables backdoor access to a compromised JBoss system. Once
compromised, the servers are often infected with a ransomware program known
as Samsam.

"I think it is very much a target of opportunity," said Matt Olney, manager
of threat intelligence analytics of Cisco's Talos group. "I don't think the
educational sector was being targeting specifically; they happen to be
running JBoss and they got caught up in this activity."

While schools and healthcare facilities have been hacked in the past,
ransomware infections are less common. Over the past year, however,
crypto-ransomware attacks have become more frequent, hitting businesses,
consumers, government offices, schools and, most recently, hospitals.

Most ransomware relies on tricking a user into running a program that
infects the victim's system. Samsam, however, infects servers directly
using a year-old vulnerability that became widely known in November
<https://foxglovesecurity.com/2015/11/06/what-do-weblogic-websphere-jboss-jenkins-opennms-and-your-application-have-in-common-this-vulnerability/>.
The vulnerability occurs in the way that some application servers—including
JBOSS, WebSphere and Weblogic—handle the conversion of data objects in
Java, known as unserialization. Once attackers get control of a server
through the vulnerability, they load JexBoss onto the server to allow easy
access through the backdoor program. The attackers then use the backdoor to
install Samsam.

In some cases, the attackers have been known to install denial-of-service
tools and Bitcoin mining tools. The attackers often reconnoiter the network
to find more potential victims for their software.

The attackers installing the JexBoss backdoor and the Samsam malware may
not be the same group, Olney said. "We've seen multiple people use the same
backdoor on a particular system," he said. "The Samsam actor is likely
using some pre-existing backdoor to get into the system."

Cisco also warned the maker of a library management system
<http://blog.talosintel.com/2016/04/jboss-backdoor.html> that runs on JBoss
that it appeared to be vulnerable to the flaws. The management system is
often used by school libraries, the company said. Once Samsam is installed,
it requires no action by the operators.

SamSam and another recent ransomware program known as Maktub do not require
a connection to a command-and-control server
<http://blog.checkpoint.com/2016/03/28/check-point-threat-alert-samsam-and-maktub-ransomware-evolution/>
to encrypt data on a targeted system. Internet-connected JBoss servers
still vulnerable to the Java unserialization flaw pose a serious hazard for
the organizations that own the computers.

Because anyone can scan for signs of the vulnerabilities, such servers are
easy to target—and many attackers have, Cisco said. "[W]e've learned that
there is normally more than one webshell on compromised JBoss servers," the
company stated in its post, adding that it has seen a variety of backdoors
on the same server with names such as "mela," "shellinvoker,"
"jbossinvoker," "zecmd," "cmd," "genesis," and "sh3ll." "This implies that
that many of these systems have been compromised several times by different
actors," the company said.
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