New Low-Level Binaries

Affected Platforms

Clients - Windows 7
Servers - Windows Server 2008 R2

Feature Impact

Severity - Medium
Frequency - High


To improve internal engineering efficiencies and improve foundations for future work, we have relocated some functionality to new low-level binaries. This refactoring will make it possible for future installs of Windows to provide subsets of functionality to reduce surface area (disk and memory requirements, servicing, and attack surface).

Manifestation of Impact

As an example of functionality that we moved to low-level binaries, kernelbase.dll gets functionality from kernel32.dll and advapi32.dll. This means that the existing binary now forwards calls down to the new binary rather than handling them directly; the forwarding can be static (the export table shows the redirection), or runtime (the dll has a stub routine that calls down to the new binary). This will impact low-level applications such as security and backup applications that are dependent upon internal APIs and offsets.


The only impact is to code that makes assumptions when attempting to look at the kernel32.dll or the advapi32.dll export table in memory, such as an anti-virus application might do. Use published APIs and not the details of their implementation. This is just one example of implementing around a detail of implementation for an API.