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

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

2013-11-03 Thread Stefan Kanthak

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

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

2013-11-03 Thread Mario Vilas

This may be a silly question, so I apologize in advance, but that would
exactly be the advantage here? Using a NULL pointer is in most (if not all)
those cases undocumented behavior to begin with. Unless I'm missing
something, the problem is not so much with Win32 as it is with the C
language in general...


On Sun, Nov 3, 2013 at 4:30 PM, Stefan Kanthak stefan.kant...@nexgo.dewrote:

 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/




-- 
“There's a reason we separate military and the police: one fights the enemy
of the state, the other serves and protects the people. When the military
becomes both, then the enemies of the state tend to become the people.”
___
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

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

2013-11-03 Thread Stefan Kanthak

Mario Vilas mvi...@gmail.com wrote:

 This may be a silly question, so I apologize in advance, but that would
 exactly be the advantage here? Using a NULL pointer is in most (if not all)
 those cases undocumented behavior to begin with. Unless I'm missing
 something, the problem is not so much with Win32 as it is with the C
 language in general...

For many of the Win32 functions I referenced here the behaviour of a NULL
pointer is but documented:

http://msdn.microsoft.com/en-us/library/ms647492.aspx

| If lpString is NULL, the function returns 0.

JFTR: I suspect that this is the reason why most of the other functions
  treat a NULL pointer as an empty string.

http://msdn.microsoft.com/en-us/library/ms647487.aspx
http://msdn.microsoft.com/en-us/library/ms647490.aspx
http://msdn.microsoft.com/en-us/library/ms647491.aspx

| When this function catches SEH errors, it returns NULL without null-
| terminating the string and without notifying the caller of the error.

http://msdn.microsoft.com/en-us/library/ms682425.aspx

| BOOL WINAPI CreateProcess(
|   _In_opt_ LPCTSTR lpApplicationName,
|   _Inout_opt_  LPTSTR lpCommandLine,

BOTH string arguments may be NULL!
Idem for the other CreateProcess*() functions.

http://msdn.microsoft.com/en-us/library/ms645505.aspx

| The dialog box title. If this parameter is NULL, the default title is Error.

http://msdn.microsoft.com/en-us/library/aa364934.aspx

| To determine the required buffer size, set this parameter to NULL and the
| nBufferLength parameter to 0.


Most of the Get*() functions return the required buffer size when the size
argument is 0 (or to small), but only
http://msdn.microsoft.com/en-us/library/ms724301.aspx explicitly says:

| If lpBuffer is NULL, this parameter must be zero.

and checks this contraint properly.


The problem is not the C language!
The problem is the inconsistent (and sloppy) implemenation of similar
functions of the Win32 API and their inconsistent and sloppy documentation.

regards
Stefan Kanthak


On Sun, Nov 3, 2013 at 4:30 PM, Stefan Kanthak stefan.kant...@nexgo.dewrote:

 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

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

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

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

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