Microsoft has announced that it is conducting an experiment in its Edge browser that involves disabling a historical browser feature created to improve performance, in order to allow more advanced security updates.
Specifically, this project that has been dubbed “Edge Super Duper Secure Mode”, seeks to see how the browser works if support for JIT (Just-In-Time) is disabled within V8, Edge browser’s JavaScript engine, according to information from Johnathan Norman, Head of Vulnerability Research at Microsoft Edge.
As The Record Media explains, although JIT is unknown to most end users, plays a crucial role in today’s web browsers. JIT works by taking JavaScript and compiling it into machine code in advance.
Happy to share a little experiment we are trying. https://t.co/70y6Go7JEA I am not sure if it will stick but we will see. Here is how I personally think about the matter 1 /?
– Johnathan Norman (@spoofyroot) August 4, 2021
The complexity of JIT in V8 and its security problems
According to Johnathan Norman, JIT support in V8 is complex. According to the manager, JIT-related security issues amounted to 45% of all V8 vulnerabilities in 2019.
Norman said recent tests by Edge’s team have shown that, despite its pivotal role in accelerating browsers in the early and mid-2010s, JIT is no longer a critical feature for Edge performance.
With this information in hand, Norman said the Edge team is now working in Super Duper Secure mode, an Edge setting. in which JIT is disabled and three other security features are enabled such as Control Flow Enhancement Technology (CET) and Arbitrary Code Protection (ACG), two features that would not be supported by the V8 JIT implementation.
Super Duper Secure mode is currently classified as an experiment, and there are no plans yet to make it available to users. Despite this, the feature is now up and running and ready for testing. Edge Canary, Dev and Beta users can go to the following address and enable it in their browsers:
edge://flags/#edge-enable-super-duper-secure-mode
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JIT is no longer essential for browser speed
They explain from Microsoft that the performance technology “just-in-time compilation” (JIT) was introduced to browsers in 2008 to speed up specific tasks in JavaScript. JIT-enabled engines take free-type JavaScript and compile it into machine code just before it is needed. This process is sometimes called “speculative optimization”.
JavaScript code is optimized through a series of complex processing channels. These changes result in a “pretty impressive” performance increase, in the literal words of the Redmon firm’s spokespersons. Developers have made JavaScript performance comparable to C ++. But all this led to more security patches as the developers of the browser have verified.
Traditionally, browser developers they would be willing to accept this cost because users want their browsers to be “fast”, but what if we just disable the JIT? “This reduction in attack surface has the potential to significantly improve user security; it would eliminate roughly half of the V8 bugs that need to be fixed. For users, this means less frequent security updates and fewer emergency patches needed. “, they conclude from Microsoft.