“Secure”… not a chance. Flash was a tyre fire and even Adobe would say so. They did their best with massive resources, and still couldn’t claim it was secure. Please please please don’t claim this project is secure. It isn’t.
Multiple times, single devs working solo, wrote full flash interpreters over a few month.
Adobe just doesn't know what they're doing. Look how they cratered cold fusion too.
They also had a security / license daemon, lmgrd. What a joke, used MAC addresses for license issuance, was buggy, could be defeated with a simple ifconfig command.
This is the same company that assigned a whopping 0.5 FTE to porting the Director plugin from OS9 to OSX, which subsequently took years and killed the platform.
I would not make the assumption that Flash development was well resourced. Which is a shame because despite the bad rep it was an amazing tool for creatives.