Download Security

Hi there,

 

What is the safest means to download something off the internet. I know of course that I should only download file from trusted sources and nothing is 100% safe but is there a 99% solution?  For instance, if I was receiving something from a friend, how could I be sure that there wasn't malaware inadvertantly attached to the file that the person was unaware off?  What about file hosting sites like sendspace or usendit? Are those safe?

 

Whenever I have download something, I create a "scan" folder, download the file into that and then scan the folder with NIS and Malwarebytes.  Once the folder comes up clean, I open it up and scan the individual file....is that good enough?  I also notice that I Windows runs a security scan (or is that NIS?) everytime I agree to download something....

 

Another question I have is when the malware (if any) will go active?  Is it the moment it is downloaded or is it when I access the file itself (ie. click or run it..etc.)  Also, will opening an email in itself trigger a virus, or do you have to click on the link/download attachment to get infected?

 

Sorry for all the questions but I appreciate the help.

 

Thanks!