One of the methods that anti-spyware programs use to block the installation of spyware is to modify the Windows hosts file. By placing a malicious website in the hosts file and directing it to 127.0.0.1 (your computer); mislabeled email links, web site banner ads, etc. that point to evil sites are not rendered in the web browser (which is one way they can damage your computer). Websites such as the Internet Storm Center, http://isc.sans.org/, compile lists of web sites that are engaged in criminal activity, plant spyware and viruses, hijack browsers, scan ports, etc.; these lists are used by network administrators to protect business networks. Another site where you can learn more is http://www.bleedingsnort.com/

The list of sites in blockedhosts.txt includes ad servers, many of which use tracking cookies. You may erase a line in the hosts file if you would like to see ads from that server, just don't leave a line blank. The other sites listed in the file are associated with phishing, worms, viruses and spyware installations. The list was last updated on 18 November 2006 (and includes the blocking of sites that Symantec listed in their many threat analyses).

First you will need to download blockedhosts.txt (89,911 bytes) to your desktop (to save it as a text file, right click on the link and then click Save As). Then, follow these step-by-step instructions in order to add a new layer of protection to your computer:

1. Left click the green Start button.
2. Right click Explore.
3. Left click the Tools pull down menu, and click Folder Options.
4. Left click the View tab in the Folder Options dialogue box.
5. Uncheck the Hide extensions for known file types check box (if it is checked), uncheck the Hide protected operating system files check box, check the Display the contents of system folders check box, click the Show hidden files and folders radio button and click the OK button.
6. Use the center scrollbar and Scroll down until the Windows folder is visible in the left window pane.
7. Left click the plus sign (+) next to the Windows folder.
8. Use the center scrollbar and Scroll down until the system32 folder is visible in the left window pane.
9. Left click the plus sign (+) next to the system32 folder.
10. Use the center scrollbar and Scroll down until the drivers folder is visible in the left window pane.
11. Left click the plus sign (+) next to the drivers folder.
12. Left click the etc folder.
13. On your desktop, right click on the blockedhosts.txt file, and then left click Copy.
14. Right click in the right window pane below the files listed in the etc folder, and left click Paste.
15. Right click on the hosts file (the one with no file extension) and left click Rename.
16. Type in "hostsold.txt" and rename the file (this will allow you to reverse the process if you desire).
17. Click Yes on the Confirm File Rename dialogue box.
18. Right click on the blockedhosts.txt file and left click Rename.
19. Rename the file "hosts" (with no .txt extension).
20. Right click on the hosts file (the one now with no file extension) and left click Properties.
21. In the hosts properties dialogue box, check the Read Only check box.
22. Click the Apply button, then click the OK button.

If you are using Lavasoft's Ad-Aware SE Plus you can also add bad domains to the list of sites that it blocks. Right click and Save As sites.txt. Then open Ad-Watch SE Plus, click the Tools button, click the Popups button, click the Import Sites link and load sites.txt. Sites.txt (11-18-2006) includes Ad-Aware's default list, plus the entries from blockedhosts.txt.