In less than 20 days around 8,000 Australian Internet users may have their Internet connections “severely crippled”.
Australia is the world’s tenth largest host of IP addresses that still connect to servers the FBI commandeered in 2011 to keep malware victims online, according to the DNSChanger Working Group’s figures.
The Australian Media and Communications Authority (ACMA) issued a reminder last week that up to 7,500 Australian Internet users’ would be affected when the Internet Systems Consortium on July 9 switches off DNS servers currently under its control.
The ISC was granted control over US-based DNS (domain name service) servers in November 2011 after the FBI shutdown a click fraud botnet operation run by Rove Digital, an Estonian marketing and web hosting company.
The DNSChanger malware altered the DNS settings of an infected machine to call DNS servers controlled by the botnet’s operators, allowing the attackers to serve fraudulent ads.
The DNSChanger Working Group’s latest count looks at unique IPs rather than end users and is slightly higher than ACMA’s estimate, with Australian unique IP “infections” at just above 8,500. The working group also counted 19,500 infections for Britain, and the US with over 69,500.
One problem with using the term “infection”, however, is that even users who have removed the malware could still be affected by the July 9 switch off.
The key issue is whether, after removing DNSChanger, the user restored their DNS settings to the state before the infection. If they did not, it’s like the ISC-supported connection will be disrupted.
Cameron Camp, a researcher for security firm [[xref: http://blog.eset.com/2012/05/31/dnschanger-%E2%80%98temporary%E2%80%99-dns-servers-going-dark-soon-how-to-check-your-computer |ESET|]], provides instructions on how to check and restore Windows 7 DNS server settings here, suggesting it should be set to “Obtain DNS server address automatically” rather than “preferred” or “alternate” DNS server addresses.
If the DNS server is set to a range of addresses that falls within those currently under the ISC’s control, the user is likely to face the connectivity woes the ACMA warned about.
Another possibility is that a victim’s router has been compromised, which will spell trouble for all devices that connect to the Internet through that router.
Efforts to alert potential victims of the DNSChanger malware have ramped up in recent weeks with Google and Facebook issue warnings to their users when a computer appears to be infected.
The latest figures by the ACMA suggest that public awareness campaigns have had some effect as the deadline nears.
In March the figure for Australian unique IPs still reaching out to the ISC controlled DNS servers was closer to 10,000, down from about 14,000 a month earlier.