OpenDNS — is blocking the Flashback Trojan:
So easy to setup OpenDNS.
Use OpenDNS for better speed, more security, includes anti phishing filters, no more browser redirects, blocks the Flashback Trojan, and it's free.
Open System Preferences / Preferences then select the Network tab. Click the Advanced tab then click the DNS tab.
Enter these addresses exactly as you see them here.
Then click OK.
More about OpenDNS here.