HP has released SWFScan, a free static code analysis tool for Flash. It does decompiling and static code analysis for a pretty huge list of vulnerabilities in Flash. Supports up to ActionScript 3.
Using it is easy: point it to the flash file, click on "Get" to retrieve and decompile, then click on "Analyse" to well...Analyse the source code :)
Decompiled source codes can be saved, and a HTML vulnerability report can be generated too after analysis.
FAQ
http://www.communities.hp.com/securitysoftware/blogs/spilabs/archive/2009/03/20/hp-swfscan-faq.aspx
Blog post
http://www.communities.hp.com/securitysoftware/blogs/spilabs/archive/2009/03/20/exposing-flash-application-vulnerabilities-with-swfscan.aspx
Download
