Inscription: Thwarting ActionScript Web Attacks From Within

The design and implementation of Inscription, the first fully automated Adobe Flash binary code transformation system that can guard major Flash vulnerability categories without modifying vulnerable Flash VMs, is presented and evaluated. Inscription affords a means of mitigating the significant class of web attacks that target unpatched, legacy Flash VMs and their apps. Such legacy VMs, and the new and legacy Flash apps that they run, continue to abound in a staggering number of web clients and hosts today; their security issues routinely star in major annual threat reports and exploit kits worldwide. Through two complementary binary transformation approaches based on in-lined reference monitoring, it is shown that many of these exploits can be thwarted by a third-party principal (e.g., web page publisher, ad network, network firewall, or web browser) lacking the ability to universally patch all end-user VMs-write-access to the untrusted Flash apps (prior to execution) suffices. Detailed case-studies describing proof-of-concept exploits and mitigations for five major vulnerability categories are reported.