Adjust Process Security is an action that allows a process to be protected from tampering by users.
The existing Adjust Process Rights [[Security]] action in v8.0 would elevate the integrity level of processes if an integrity level SID was specified, but would not lower the integrity level in “decrease mode”. This feature has been implemented. [[Meaning it now will lower the integrity level in "Decrease Mode"?]]
Restricted SIDs
As well a less well known (and used) feature has been added: Restricted SIDs. This feature is just exposed as an option “Restricted Code” on the Adjust Process Rights action.
The main intended usage of Restricted SIDs is the Well Known SID RESTRICTED_CODE (RESTRICTED). Technically when evaluating security for any operation, when there is any Restricted SID specified then not only does the Security Descriptor need to allow access to the user, but also explicitly to the Restricting SID.
Generally in usage this mechanism basically removes all ability for a program to execute at all. Microsoft recognised the practical limitations of this mechanism and introduced a tweak that only applies the Restricted SID functionality to WRITE operations. Our Restricted Process option leverages this functionality.
So whilst a Restricted Process would be able to read any local resources the user could read (unless banned by deny Security Descriptors), any ability to write to resources is protected.
Another benefit of this is that Restricted Processes do not have rights to open any network based resource (e.g., file servers).