[Full-disclosure] Defense in depth -- the Microsoft way (part 13): surprising and inconsistent behaviour, sloppy coding, sloppy QA, sloppy documentation

Hi @ll,

the Win32 API is full of idiosyncrasies resp. surprising and inconsistent,
poorly tested and documented behaviour.

Just to pick one: NULL pointer as string argument.

0. lstrlen(NULL)
lstrcat(NULL, ...) and lstrcat(..., NULL)
lstrcmp(NULL, ...) and lstrcmp(..., NULL)
lstrcmpi(NULL, ...) and lstrcmpi(..., NULL)
lstrcpy(NULL, ...) and lstrcpy(..., NULL)
lstrcpyn(NULL, ..., 0) and lstrcpy(..., NULL, ...)

do not yield an exception, but treat their NULL arguments like an
empty string (when used as source), resp. return NULL (when used as
destination).


1. wsprintf(NULL, ...) and wvsprintf(NULL, ...)
wsprintf(..., NULL, ...) and wvsprintf(..., NULL, ...)

yield an access violation in USER32.DLL.


2. CommandLineToArgvW(NULL, ...)

yields an access violation in SHELL32.DLL.


3. CreateProcess(NULL, NULL, ...)
CreateProcessAsUser(..., NULL, NULL, ...)
CreateProcessWithLogonW(..., ..., ..., ..., NULL, NULL, ...)
CreateProcessWithTokenW(..., ..., NULL, NULL, ...)

yield an access violation in KERNEL32.DLL.


4. GetFileAttributes(NULL)

does not yield an exception, but treats the NULL argument like an
empty string.


5. GetBinaryType(NULL, ...)

does not yield an exception, but treats the NULL argument like an
empty string.


6. MessageBox(..., NULL, ...) and MessageBox(..., ..., NULL, ...)

do not yield an exception, but treat the NULL argument like an
empty string.


7. FatalAppExit(0, NULL)

does not yield an exception, but treats the NULL argument like an
empty string.


8. GetCurrentDirectory(..., NULL)

returns an error if the buffer size (the argument shown as ... here)
is sufficient to hold the result, else the required buffer size.

GetTempPath(..., NULL)
GetSystemDirectory(NULL, ...)
GetSystemWindowsDirectory(NULL, ...)
GetSystemWow64Directory(NULL, ...)
GetWindowsDirectory(NULL, ...)
GetComputerName(NULL, ...)

yield an access violation in NTDLL.DLL resp. KERNEL32.DLL if the
buffer size is sufficient to hold the result, else the required
buffer size.

GetUserName(NULL, ...)
GetComputerObjectName(..., NULL, ...)

do not yield an access violation, but return an error with
GetLastError() == ERROR_INSUFFICIENT_BUFFER.


9. GetUserName(NULL, NULL)
GetComputerName(NULL, NULL)

yield an access violation in KERNEL32.DLL.

GetComputerNameEx(..., NULL, NULL)
GetComputerObjectName(..., NULL, NULL)

do not yield an access violation, but return an error with
GetLastError() == ERROR_INVALID_PARAMETER.

JFTR: only the documentation of the last function (see
<http://msdn.microsoft.com/en-us/library/ms724301.aspx>)
explicitly says about the value of the third argument
"If lpBuffer is NULL, this parameter must be zero."
and checks this contraint properly.


The expected behavior in all cases is but to return an error with
GetLastError() == ERROR_INVALID_PARAMETER or similar.


FIX: ALL interfaces of the Win32 API should^WMUST verify (ALL) their
arguments properly before using them and return an appropriate,
documented error code.


stay tuned
Stefan Kanthak

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/