selfdeleting dll possible?

This is a discussion on selfdeleting dll possible? within the Windows Programming forums, part of the Platform Specific Boards category; I know that executables can delete themself, now i want that a into a process loaded dll does a self ...

  1. #1
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    selfdeleting dll possible?

    I know that executables can delete themself, now i want that a into a process loaded dll does a self deletion. i'm coding the dll in unicode.

    here is a short code snippet that works for a standalone executable

    Code:
        BOOL SelfDelete() 
       { 
          TCHAR szFile[MAX_PATH], szCmd[MAX_PATH]; 
    
          if ((GetModuleFileName(0, szFile, MAX_PATH) != 0) && 
             (GetShortPathName(szFile, szFile, MAX_PATH) != 0)) 
          { 
             lstrcpy(szCmd, "/c del "); 
             lstrcat(szCmd, szFile); 
             lstrcat(szCmd, " >> NUL"); 
    
             if ((GetEnvironmentVariable("ComSpec", szFile, MAX_PATH) != 0) && 
                 ((INT)ShellExecute(0, 0, szFile, szCmd, 0, SW_HIDE) > 32)) 
             return TRUE; 
          } 
          return FALSE; 
       }
    and the bool to trigger the function:
    Code:
          if (!bWhatImCheckingHere(myparam1, myparam2, myparam3, myparam4, myparam5)) 
          { 
             SelfDelete(); 
             ExitProcess(0); 
             //shutdownpc();//shutdowns pc if wrong serial 
          }
    this code above works also for a executable, because after the selfdelete call, i do a exitprocess call to the target process.

    here is the code i use to get the path and name of the dll
    Code:
    BOOL APIENTRY DllMain(HMODULE hDll, DWORD Reason, PVOID lpReserved) 
    { 
       if (Reason == DLL_PROCESS_ATTACH) 
       { 
          GetModuleFileNameA((HMODULE)hDll, bfr, sizeof(bfr)); 
    
          DisableThreadLibraryCalls(hDll); ....u.s.w.
    Code:
    FILE *pDLLFile;//pointer to DLL 
    ... 
    
    pDLLFile = fopen(bfr, "rb");//open .DLL for read in binary mode
    i have used another code in my loaded dll, but all the dll did, was to delete the binary file of the target process on the hard disk.
    i want that the loaded dll, deletes itself and exits the process. it does all that, except the self deletion.

    any help, tips, hints and push into the right direction is more than welcome

  2. #2
    erstwhile
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    >>I know that executables can delete themself, now i want that a into a process loaded dll does a self deletion.<<

    And why do you want to do this?

    This is a windows question anyway, so it's off to the windows board.
    CProgramming FAQ
    Caution: this person may be a carrier of the misinformation virus.

  3. #3
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    I have a dll i distribute to a few customers, they pay for the functions of the dll. the community that is interested in the functions of my dll, this community has a realy big problem with leakers. they just steal your work and in some cases they even edit ressources of your binarys and claim thats their work. that was one of the many reasons i have implemented a self file validation check to my dll and exe files and i have implemented a hardwarebased antileak protection and some other checks i wont mention here. you can calm down, this self deletion of my dll is never meant to harm anyone, i know how to wipe whole drives, but this is not my goal. i only want that my dll does itself delete if some unauthorized persons try to use the dll, that's all. and sry, when i've posted in the wrong forum, didn't knew i have posted in the wrong forum.

    ok, so far i've came up with this code:

    Code:
    	BOOL SelfDeleteDll()
    	{
    		TCHAR szCmd[MAX_PATH];
    
    		if ((GetModuleFileNameW((HMODULE)hDll, path, sizeof(path)) != 0) && 
    		    (GetShortPathNameW(path, path, sizeof(path)) != 0))
    		{
    			lstrcpy(szCmd, L"/c del ");
    			lstrcat(szCmd, path);
    			lstrcat(szCmd, L" >> NUL");
    
    			if ((GetEnvironmentVariable(L"ComSpec", path, MAX_PATH) != 0) && 
    			    ((INT)ShellExecute(0, 0, path, szCmd, 0, SW_HIDE) > 32))
    			return TRUE;
    		}
    		return FALSE;
    	}
    Code:
          if (!bWhatImCheckingHere(myparam1, myparam2, myparam3, myparam4, myparam5)) 
          { 
             SelfDeleteDll(); 
             ExitProcess(0); 
             //shutdownpc();//shutdowns pc if wrong serial 
          }
    but it's not working!

    i have now added a messagebox that displays me path and command, this is the result:
    MessageBox(NULL, path, TEXT("Test"), 0);
    result of msgbox is: C:\WINDOWS\system32\cmd.exe

    MessageBox(NULL, szCmd, TEXT("Test"), 0);
    result of msgbox is: /c del D:\PROGRA~1\MyTest~1\Folder\Test.exe >> NUL

    test.exe is the target process
    and path is:
    TCHAR path[MAX_PATH];

    the crazy thing is, when i use only GetModuleFileNameW msgbox shows the exact path to my dll.
    Last edited by Salem; 08-26-2006 at 04:50 AM. Reason: Folding long lines - avoid tabs in code

  4. #4
    and the hat of wrongness Salem's Avatar
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    Anyone smart enough to figure out how to edit resources in files is probably smart enough to find an "undelete" utility (or just look in the trash can).

    Or maybe the easier way of making the COMSPEC environment variable point at an executable which does nothing.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  5. #5
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    first off, it doesnt delete the file into the trashcan, 2nd: i dont care if they want to use any "undelete" utilitys, just so you know you can advance the code and let it secure delete ala gutman methode. 3rd: i let the target process exit and then immediately shutdown their pc's and if that $hit is not enough, i just let my dll format their crappy plate. 4rd: dll is encrypted and compressed with an custom non public software and code, 5th: i'm using hardwarebased and ipbased antileak and self file checksum validation, 6th: the final dll is inside a loader.exe as a byte array header file, makes it impossible to use a ressource editor to even get the dll, the loader.exe is too heavily protected. 7th: i'm using antidump techniques, 8th: im using antidebug and antidessamble code and 9th: if thats not enough i would say /*mod edit for offensive language*/ leakers. 10th: the file is not publicaly distributed, it is hand out by myself to a few people. all i wanted is to figure out, if it's possible to use self deletion code in a dynamic link library and not only for a executable, for the executable it works very good. and now have a nice day, klugscheisser.
    Last edited by Ken Fitlike; 08-26-2006 at 07:18 AM. Reason: offensive language removed

  6. #6
    and the hat of wrongness Salem's Avatar
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    Wow
    *plonk*
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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