I wish to analyze the changes made by a specific virus. For example, Win32.Sality.
Where can I get the sample of this, or other similar, malware for testing?
virusshare.com is another great repository of malware samples, having a huge number of samples. A snapshot from the website's homepage:
Access is by invitation only, so you will need to drop a mail to the site admin.
Another good resource that I know of- www.deependresearch.org
Here Are Some List of sites where you can get malware for samples
MalwareTIps - Virus exchange Forum
The above url's are An Summary from here
Hope it helps