From everything I've gathered, most up-to-date anti-virus and anti-spyware should detect this. The problem is that the DNSChanger redirects away from anti-malware update sites. I personally recommend either scanning from a bootable CD/DVD (BartPE, UBCD4Windows, etc.) or pulling the drive to scan it from a clean, updated system.
Apple has an antivirus tool out that is supposed to remove it from their OS. http://www.apple.com/downloads/macosx/networking_security/iantivirus.html
Block and/or monitor all traffic to and from 85.255.112.0 – 85.255.127.255 (85.255.112.0/20).
http://isc.sans.org/diary.html?storyid5434<br />
http://www.symantec.com/security_response/writeup.jsp?docid
2008-120318-5914-99&tabid''2<br />
http://asert.arbornetworks.com/2008/11/rogue-dns-servers-on-the-move/
– Main.FredPettis - 03 Apr 2009