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DNS Changer Trojan Horse – SecureMac Removal Instructions and Anniversary Followup

Posted on December 17, 2008

SecureMac Security Bulletin

Posted: December 17th, 2008

Security Risk: Critical

Halloween marked the one-year anniversary since the DNSChanger Trojan Horse was discovered in the wild, and in that time it has grown to become the single most widespread piece of malware on OS X. In order to promote safe web browsing, SecureMac has issued a bulletin on the DNSChanger Trojan Horse, with information on common symptoms of infection, ways to check for and remove the Trojan, and a list of safe practices when surfing the web.

Symptoms of Infection by DNSChanger Trojan Horse

  1.     Website links are redirected. When you click on a link to a website (in search engine results, for example), you will be redirected to a different site, generally advertising sites.
  2. Pop-up advertisements. Infected computers will sometimes display advertisements, including pop-up ads, usually for pornographic websites or enhancement drugs.
  3. Web pages load slowly. Web pages may take a long time to load, or time out completely when infected with the trojan horse.

Removing the DNSChanger Trojan Horse

You can remove the DNSChanger Trojan Horse with our free removal tool, available at

Additionally, MacScan removes the DNSChanger Trojan Horse and thousands of other trojan horses, keyloggers, and tracking cookies. More information on MacScan is available at

Safe Web Browsing Habits

  1. Watch where you surf. By sticking with safe, well-known websites, you will be less likely to visit a site that will attempt to infect you with the trojan horse.
  2. Watch what you download. Download files only from trusted sources and safe sites.
  3. Use security features in OS X. Turn on the built-in Firewall, and consider security software, especially when a computer is shared by multiple users.

Update! DNSChanger Trojan Horse has evolved over time with the functionality to now execute malicious code downloaded from remote servers. This increases the severity of the threat.

For further security information, visit

About MacScan

MacScan quickly detects, isolates and removes spyware from Macintosh computers using both real-time spyware definition updating and unique detection methods.  The software also manages internet-related clutter on your computer. It is designed for Mac OS X version 10.2.4 and later, and is compatible with OS X 10.5 (Leopard). For more information, or to download a demo version of MacScan, visit

About SecureMac

Since 1999, has been at the forefront of Macintosh system security. The site not only features complete Macintosh Anti-Spyware and Antivirus solutions, but also operates as a clearinghouse for news, reviews and discussion of Apple computer security issues. Users from novice to the most advanced will find useful information at SecureMac that is designed to make their computer experience trouble free.

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