Freely subscribe to our NEWSLETTER

The DNS Changer Remediation Study identified phone calls, billing notices and redirecting users to customized Web pages among the most effective methods to notify customers that their systems were infected. Researchers Wei Meng and Ruian Duan, working under the supervision of Georgia Tech School of Computer Science Professor Wenke Lee, also found that "active" social media warnings were useful for enabling remediation. With this approach, sites such as Google directly informed users they were infected through their browser windows, a tactic that proved to be more effective in motivating users to disinfect their systems than passive warnings issued in general posts or news articles on social media platforms.

"Social media can have an important role to play in alerting users to infections in their systems and in stemming malware outbreaks. We believe in the importance of implementing active, direct notifications earlier in the process," Lee said.

The researchers looked at both various types of end-user alerts and network operators’ efforts to help customers disinfect their systems, including using walled gardens, DNS redirection, anti-virus software and malware removal tools. Part of the challenge facing the industry from bots is determining how to notify users their systems have been compromised in a timely and credible manner, then assisting non-technical customers in remediating those machines, according to M3AAWG Co-Chairman Michael O’Reirdan.

O’Reirdan said, "The industry’s response to the DNS Changer malware clearly showed how well competitors and vendors can work together when users’ safety is on the line. It also was an extraordinary opportunity to objectively study the different approaches companies have developed to assist customers and to understand the important role each of us plays in safeguarding the online experience. The active involvement of anti-malware and security tool vendors, social media platforms, law enforcement, operating system vendors and home networking technology vendors has been shown to be crucial. In the end, it takes the entire Internet ecosystem working together to protect end-users."

The data used in the study to determine infection and cleanup rates was provided anonymously from major ISPs around the world through the DNS Changer Working Group (DCWG) to the research team at the Georgia Tech Information Security Center (GTISC). To identify the different types of notification and mediation techniques used, the researchers sent questionnaires asking network operators how they had alerted customers who were infected with the DNS Changer malware and the specifics around the remediation efforts employed by each ISP to assist customers in cleaning their machines. An ISP that did not take any action in response to the malware became the baseline for measuring the effectiveness of the other approaches, according to Lee.

From 2007 to 2011, the DNS Changer Trojan hijacked Internet searches and re-routed the Web browsers of infected computers to fraudulent sites using the rogue DNS servers operated by the Rove Digital advertising network. However, if the rogue DNS servers had been turned off when the allegedly responsible Estonians were arrested, infected end-users would not have been able to reach the Web. The DCWG was a group formed to assist law enforcement in dealing with the potential end-user issues arising from the law enforcement action. The DCWG also helped operate and monitor the "clean" DNS servers that were operated legally by the Internet Systems Consortium (ISC) under a U.S. court order from November 2011 to July 2012. As a result, instead of suddenly losing access to the Internet, millions of users were notified they were infected and needed to clean up their machines.

The complete DNS Changer Remediation Study is available on the M3AAWG website at https://www.maawg.org/sites/maawg/files/news/GeorgiaTech_DNSChanger_Study-2013-02-19.pdf.