Microsoft Edge; Google's Project Zero team has released a number of details that help circumvent an important Edge security technique.
Let's see what the problem is:
Arbitrary Code Guard (ACG), was released with the release of Windows 10 Creators Update to help prevent attacks from the web that try to load malware code in the memory. This technique ensures that the memory only accepts properly signed code.
However, as Microsoft explains, Just-in-Time (JIT) compilers used in modern web browsers pose a problem for ACG. JIT compilers convert JavaScript into native, unsigned code.
So to ensure that JIT compilers continue to run even when ACG is enabled, the company's developers split Microsoft Edge JIT into a separate process running on its own isolated sandbox.
But here came the researchers from Google's Project Zero. Researchers have found that there is a problem with the way the JIT process writes executable data to the content.
THE 'bypass the ACG using UnmapViewofFile' allows a content process to predict which address of a dwork JIT μπορεί να καλέσει το VirtualAllocEx(), αλλά και τη διεργασία περιεχομένου που ετοιμάζεται να “διαθέσει μια region εγγράψιμης μνήμης στην ίδια διεύθυνση του JIT server to an executable that will run soon”.
Google reported the issue to Microsoft in mid-November and released the details of the exploit yesterday, as the 90 days have passed.
Microsoft confirmed the ACG bypass at some point in Patch Tuesday, which was released in February. Apparently the company intended to fix the issue by then, but found it a bit "more complicated" than it initially thought.
So the solution for a secure Microsoft Edge is expected to be released with Patch Tuesday in March.
