Most of the browsers now support Flash Animations. Flash swf files can be used to hack your computer with out any action from your side. What you have to do is just visit the site that have malicious code inside it. Flash movies can download and install hacker files in your pc.
A Flash advertisement appeared last week on popular web site like USA Today, DeseretNews.com and SLTrib.com downloaded malicious code to users computers, generating erroneous warnings of a malware infestation and offering a phony solution.