Just published the 1st article In the series of articles I will be posting on InsideRIA in regards to Flash/Flex security. The intention of these articles is for you to gain knowledge about security in regards to Flash and Flex applications. In each article I will be covering specific security vulnerabilities, showing examples of how an attacker can abuse Flash/Flex applications, and pointing out ways to help prevent these attacks. The purpose of these articles is to increase awareness so you will take security into consideration when building your applications.

See the first article that talks about Cross-domain Scripting threat here:
http://www.insideria.com/2009/12/top-security-threats-to-flashf.html