While investigating activity associated with the RIG exploit kit, researchers at Cisco managed to cause some damage to an operation, but an uncooperative service provider prevented them from completely shutting it down.
RIG has been around for several years and while it’s not as popular as the Angler exploit kit, it’s still successfully used by cybercriminals to deliver malware. Over a two-month period in the fall of 2015, Cisco researchers observed a campaign in which hundreds of users were being redirected to the exploit kit via malvertising attacks and malicious iframes planted on compromised websites.
Using Flash exploits, primarily for the CVE-2015-5119 vulnerability which came to light last year following the breach suffered by Italian spyware maker Hacking Team, the attackers leveraged RIG to deliver spambots such as Tofsee.
An analysis of the 44 IP addresses used to serve RIG showed that a large majority of them belonged to the same autonomous system number (ASN) associated with hosting provider Webzilla.
After being contacted by Cisco, Webzilla took steps to identify the customers responsible for the malicious activity and blocked the hosts. However, the offending IP addresses were leased to a downstream provider, Russia-based Eurobyte.
Since Eurobyte failed to respond to Cisco’s notifications, the attackers continued to set up new servers.
“This underscores one of the major problems we face today, leaf providers. As providers could have multiple downstream leaf providers we find that we routinely have success in dealing with larger providers. These providers help get systems shut down, but without the cooperation of the smaller downstream providers the adversaries just stand up new servers and move on,” Cisco researchers explained in a blog post. “We were able to inflict some damage to RIG during our investigation, but were unable to actually get the actors behind the activity stopped.”
Cisco’s investigation revealed that Eurobyte owns seven class C networks, one of which serves as their corporate network. Using the capabilities of OpenDNS, a company acquired by Cisco last year, researchers determined that five of the remaining class C address spaces had a bad reputation.
Since Eurobyte failed to cooperate, Cisco and OpenDNS decided to blacklist the five subnets for a period of 30 days in an effort to protect their customers against potential attacks.
In August, Trustwave reported that RIG 3.0 had been used to infect more than 1.3 million computers worldwide with malware. Earlier this week, Heimdal Security reported seeing an increase in RIG activity as malicious actors continue to leverage Hacking Team’s Flash Player exploits to deliver Tofsee and Pony malware.
According to Heimdal, RIG 3.0 has a success rate of 56 percent on Windows 7 machines with Internet Explorer 9.
This was not the first time Cisco targeted exploit kit activity. In October, the networking giant reported disrupting a major ransomware operation powered by the Angler exploit kit. At the time, Cisco worked with hosting providers whose services had been abused to shut down the servers used by the cybercrooks.