Amit Klein has written another fine paper involving using Flash to send http requests.
"Flash player is a very popular browser add-on from Adobe (actually,
Flash was invented by Macromedia, which was acquired by Adobe). This
write-up covers mostly Flash 7 and Flash 8, together covering more than
94% of the Internet-enabled desktops (according to NPD Online Survey
conducted April 2006, quoted in Adobe's website [1], [2]). Flash movies
are delivered as SWF (ShockWave File) files. Adobe developed a rich
Javascript-like language called ActionScript to provide scripting
capabilities to Flash. One of the interesting features of ActionScript
is its ability to send HTTP requests to 3rd party sites through the
browser which invoked it. This is where Flash becomes interesting
security-wise. With Flash it is possible to shape an outgoing request
to a 3rd party site in ways not available from within "standard"
Javascript. Specifically of interest is Flash's ability to send
arbitrary HTTP request headers with outgoing HTTP requests."
Article Link: Forging HTTP request headers with Flash
