Intercepting WinPopUp - Mailslot Tricks

Keywords: 	  mailslot

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Question:

Is it possible to write a continuous running script to intercept and write to a text file the data sent by the Winpopup function on either a Win95 or WinNT40 box? This would be used by security personnel.

Answer:

Yes. See the following 2 files. One of them can send messages, the other can receive them.

You can't have winpopup run at the same time though.

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SendMailSlot.WBT

;To write a message to a mailslot, a process uses the CreateFile function, specifying the mailslot name by using one of the following formats: 
;Format Usage 
;\\.\mailslot\name Retrieves a client handle to a local mailslot. 
;\\computername\mailslot\name Retrieves a client handle to a remote mailslot. 
;\\domainname\mailslot\name Retrieves a client handle to all mailslots with the specified name in the specified domain. 
;\\*\mailslot\name Retrieves a client handle to all mailslots with the specified name in the system's primary domain. 
;If CreateFile specifies a domain or uses the asterisk format to specify the system's primary domain, the application cannot write more than 424 bytes at a time to the mailslot. If the application attempts to do so, the WriteFile function fails and GetLastError returns ERROR_BAD_NETPATH. 
;An application must specify the FILE_SHARE_READ flag when using CreateFile to retrieve a client handle to a mailslot. 
DaDll=strcat(DirWindows(1),"kernel32.dll")
WaitForever = -1
mailslotname="\\.\mailslot\messngr"
GENERIC_WRITE = 1073741824; 0x40000000
FILE_SHARE_READ = 1
FILE_SHARE_WRITE = 2
CREATE_NEW = 1
FILE_ATTRIBUTE_NORMAL = 128

DesiredAccess = Generic_Write
ShareMode = FILE_SHARE_READ
HowCreate = CREATE_NEW ;?????
flags = FILE_ATTRIBUTE_NORMAL
handle=DllCall(DaDll,long:"CreateFileA",lpstr:mailslotname,long:DesiredAccess,long:ShareMode,lpnull, long:HowCreate, long:flags, lpnull)
msgbuf = BinaryAlloc(500)
teststring = "Testing this msg thingie. How are we doing this fine day?"
BinaryPokeStr(msgbuf, 0, teststring)
NumBytes = BinaryEODGet(msgbuf) + 1
NumBytesWritten = BinaryAlloc(10)
result = DllCall(DaDll,long:"WriteFile", long:handle, lpbinary:msgbuf, long:NumBytes, lpbinary:NumBytesWritten, lpnull)

DllCall(DaDll,long:"CloseHandle",long:handle)

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MailSlot.WBT

DaDll=strcat(DirWindows(1),"kernel32.dll")

WaitForever = -1
mailslotname="\\.\mailslot\messngr"
handle=DllCall(DaDll,long:"CreateMailslotA",lpstr:mailslotname,long:0,long:WaitForever,lpnull)

bbnextsize=BinaryAlloc(4)
BinaryPoke4(bbnextsize,0,0)
bbmsgcount=BinaryAlloc(4)
BinaryPoke4(bbmsgcount,0,0)


while 1
   rslt=DllCall(DaDll,long:"GetMailslotInfo",long:handle,lpnull,lpbinary:bbnextsize,lpbinary:bbmsgcount,lpnull)
   nextsize=BinaryPeek4(bbnextsize,0)
   msgcount=BinaryPeek4(bbmsgcount,0)
   if msgcount!=0 then break
	TimeDelay(1)
;   Display(4,nextsize,msgcount)
endwhile

BinaryFree(bbnextsize)
BinaryFree(bbmsgcount)

bbread=BinaryAlloc(nextsize)
BinaryEODSet(bbread,nextsize)
bbbytes=BinaryAlloc(4)
BinaryPoke4(bbbytes,0,0)
rslt=DllCall(DaDll,long:"ReadFile",long:handle,lpbinary:bbread,long:nextsize,lpbinary:bbbytes,lpnull)
msg=BinaryPeekStr(bbread,0,nextsize)
BinaryFree(bbread)
BinaryFree(bbbytes)
DllCall(DaDll,long:"CloseHandle",long:handle)
Message("Msg",msg)

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Article ID:   W14292

Filename:   Intercepting WinPopUp - Mailslot Tricks.txt