Windows File Protection fails to protect MSVCRT.DLL

[fjeske]

We have a XP SP2 system that was corrupted by an old product install
resulting in the problem described here:
http://support.microsoft.com/kb/324762. Notably, MSVCRT.DLL gets clobbered
by the installer. However, how can this problem occur if Windows File
Protection is enabled and is supposed to protect all system DLLs?

I understand that WFP will "notice" that a system DLL is replaced within a
minute of it's overwrite. Is it possible that a quick system reboot after
the installer finishes (typical of InstallShield) prevents the replaced DLL
from being fixed?

 

[Leonard Grey]

WFP doesn't protect "all" system files; it protects a subset of critical
system files.

"Description of the Windows File Protection feature"
http://support.microsoft.com/kb/222193

 

[fjeske]

From http://www.microsoft.com/whdc/archive/wfp.mspx:

Protected File List
All SYS, DLL, EXE, and OCX files that ship on the Windows CD are protected.
True Type fonts--Micross.ttf, Tahoma.ttf, and Tahomabd.ttf--are also
protected.

 

[Anteaus]

This is a problem as old as Windows itself; MSVCRT.DLL stands for 'Microsoft
Visual C Runtime (library)' and it's permitted for a coder to distribute this
with their software.

The modern approach is to put such support-files into the program's own
folder. That way, they affect no-one else's code. In the old days of tight
resources it was more common to put library files into the system folder so
that only one copy of each was (theoretically) needed. This did sometimes
cause version-clashes.

What is even worse is that some coders use 'broken' setup routines which
will quite happily replace a new version with an old, buggy one. This is
where the problems really start

Since this file is not part of the Windows core OS as such, it isn't
protected.