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| fra_00xx 980217 NaTzGUL 0110 OT AD | Yes, dear reader, you'll slowly learn how to program (in the most REAL sense of the word) in windows... in order to bend this overbloated operating system to your twisted purposes :-) Enjoy! It's fundamental 'required' reading... read it twice (at least) and then work on this... you'll be a much more powerful wizard when you are finished with this... |
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INTRO: Yup ! iam back from lazyness =)
Hello and Welcome to my new tut.
This time it concerns, how to access the memory of a Process, i.e. write
and read access.
This is actually nothing new and the Game Trainer Scene proves it to us daily.
The problem under win95 is actually that a Process has no rights to access
the memory of another Process (above all not the code).
In this tut I will show you methods and the functions to bypass this problem.
Lotta people has spoken about these functions, but no one did somewhat
useful with them until now (except the Trainer Scene),
however this is my contribution to fill this gap and of course a few examples
how to use them for cracking purposes were included.
Author : NaTzGUL Email : natzgul@hotmail.com HOW TO ACCESS THE MEMORY OF A PROCESS (i.e. Game Trainer,Process Patcher etc.)
TUT: At first I will list you the mentioned functions we wanna use : (These functions are actually meant for debugging) KERNEL32!ReadProcessMemory KERNEL32!WriteProcessMemory Now the Descriptions from win32.hlp:
The ReadProcessMemory function reads memory in a specified process. The entire area to be read must be accessible, or the operation fails. BOOL ReadProcessMemory( HANDLE hProcess, // handle of the process whose memory is read LPCVOID lpBaseAddress, // address to start reading LPVOID lpBuffer, // address of buffer to place read data DWORD cbRead, // number of bytes to read LPDWORD lpNumberOfBytesRead // address of number of bytes read ); Parameters hProcess Identifies an open handle of a process whose memory is read. The handle must have PROCESS_VM_READ access to the process. lpBaseAddress Points to the base address in the specified process to be read. Before any data transfer occurs, the system verifies that all data in the base address and memory of the specified size is accessible for read access. If this is the case, the function proceeds; otherwise, the function fails. lpBuffer Points to a buffer that receives the contents from the address space of the specified process. cbRead Specifies the requested number of bytes to read from the specified process. lpNumberOfBytesRead Points to the actual number of bytes transferred into the specified buffer. If lpNumberOfBytesRead is NULL, the parameter is ignored. Return Value If the function succeeds, the return value is TRUE. If the function fails, the return value is FALSE. To get extended error information, call GetLastError. The function fails if the requested read operation crosses into an area of the process that is inaccessible. Remarks ReadProcessMemory copies the data in the specified address range from the address space of the specified process into the specified buffer of the current process. Any process that has a handle with PROCESS_VM_READ access can call the function. The process whose address space is read is typically, but not necessarily, being debugged. The entire area to be read must be accessible. If it is not, the function fails as noted previously.
The WriteProcessMemory function writes memory in a specified process. The entire area to be written to must be accessible, or the operation fails. BOOL WriteProcessMemory( HANDLE hProcess, // handle of process whose memory is written to LPVOID lpBaseAddress, // address to start writing to LPVOID lpBuffer, // address of buffer to write data to DWORD cbWrite, // number of bytes to write LPDWORD lpNumberOfBytesWritten // actual number of bytes written ); Parameters hProcess Identifies an open handle of a process whose memory is to be written to. The handle must have PROCESS_VM_WRITE and PROCESS_VM_OPERATION access to the process. lpBaseAddress Points to the base address in the specified process to be written to. Before any data transfer occurs, the system verifies that all data in the base address and memory of the specified size is accessible for write access. If this is the case, the function proceeds; otherwise, the function fails. lpBuffer Points to the buffer that supplies data to be written into the address space of the specified process. cbWrite Specifies the requested number of bytes to write into the specified process. lpNumberOfBytesWritten Points to the actual number of bytes transferred into the specified process. This parameter is optional. If lpNumberOfBytesWritten is NULL, the parameter is ignored. Return Value If the function succeeds, the return value is TRUE. If the function fails, the return value is FALSE. To get extended error information, call GetLastError. The function will fail if the requested write operation crosses into an area of the process that is inaccessible. Remarks WriteProcessMemory copies the data from the specified buffer in the current process to the address range of the specified process. Any process that has a handle with PROCESS_VM_WRITE and PROCESS_VM_OPERATION access to the process to be written to can call the function. The process whose address space is being written to is typically, but not necessarily, being debugged. The entire area to be written to must be accessible. If it is not, the function fails as noted previously.
TUT: To call both functions we need : HANDLE hProcess = ? // handle of process LPVOID lpBaseAddress, = your choice // address to start reading/writing LPVOID lpBuffer, = your choice // address of buffer to read/write data DWORD cbWrite, = your choice // number of bytes to read/write LPDWORD lpNumberOfBytesWritten = NULL // actual number of bytes read/written Now, looks nevertheless already quite promising heh ;) So the only thing we need is the Handle of the Process we want to access. A Process can call "KERNEL32!GetCurrentProcess" to get a pseudo-handle of itself. This pseudo-handle has the maximum possible access to the process object (memory). If we want to address however another Process we must proceed differently. I know two methods to get a Process Handle of another Process : 1. with USER32!FindWindowA,USER32!GetWindowThreadProcessId and KERNEL32!OpenProcess 2. with KERNEL32!CreateProcess METHOD1: ---------------- A Game Trainer use this method by the way. A Process is like everything else in win95 also only an Object, this means we can open it with "KERNEL32!OpenProcess" to get a Handle. And you betterdon't forget to close it with "BOOL KERNEL32!CloseHandle (hProcess)" later on. Otherwise the Process image will remain in the memory and waste space when the Process terminates. Here is the Description of it from win32.hlp:
The OpenProcess function returns a handle of an existing process object. HANDLE OpenProcess( DWORD fdwAccess, // access flag BOOL fInherit, // handle inheritance flag DWORD IDProcess // process identifier ); Parameters fdwAccess Specifies the access to the process object. For operating systems that support security checking, this access is checked against any security descriptor for the target process. Any combination of the following access flags can be specified in addition to the STANDARD_RIGHTS_REQUIRED access flags: Access Description PROCESS_ALL_ACCESS Specifies all possible access flags for the process object. PROCESS_CREATE_PROCESS Used internally. PROCESS_CREATE_THREAD Enables using the process handle in the CreateRemoteThread function to create a thread in the process. PROCESS_DUP_HANDLE Enables using the process handle as either the source or target process in the DuplicateHandle function to duplicate a handle. PROCESS_QUERY_INFORMATION Enables using the process handle in the GetExitCodeProcess and GetPriorityClass functions to read information from the process object. PROCESS_SET_INFORMATION Enables using the process handle in the SetPriorityClass function to set the priority class of the process. PROCESS_TERMINATE Enables using the process handle in the TerminateProcess function to terminate the process. PROCESS_VM_OPERATION Enables using the process handle in the VirtualProtectEx and WriteProcessMemory functions to modify the virtual memory of the process. PROCESS_VM_READ Enables using the process handle in the ReadProcessMemory function to read from the virtual memory of the process. PROCESS_VM_WRITE Enables using the process handle in the WriteProcessMemory function to write to the virtual memory of the process. SYNCHRONIZE Windows NT: Enables using the process handle in any of the wait functions to wait for the process to terminate. fInherit Specifies whether the returned handle can be inherited by a new process created by the current process. If TRUE, the handle is inheritable. IDProcess Specifies the process identifier of the process to open. Return Value If the function succeeds, the return value is an open handle of the specified process. If the function fails, the return value is NULL. To get extended error information, call GetLastError. Remarks The handle returned by the OpenProcess function can be used in any function that requires a handle to a process, provided the appropriate access rights were requested.
TUT: To call this function we need : DWORD fdwAccess = PROCESS_ALL_ACCESS (Thx to Micro$oft ;) // access flag BOOL fInherit = FALSE // handle inheritance flag DWORD IDProcess = ? // process identifier Use "KERNEL32!GetCurrentProcessId" to get an ID of the current Process. To get the ID of another Process we must proceed differntly again. To find out if a certain Process allready exist we call USER32!FindWindowA which will look for a Window with a certain title and then return its handle. With this window handle we then finally call GetWindowThreadProcessId to get the process identifier. Here is the Description of both function from win32.hlp:
The FindWindowA function retrieves the handle of the top-level window whose class name and window name match the specified strings. This function does not search child windows. HWND FindWindowA( LPCTSTR lpClassName, // address of class name LPCTSTR lpWindowName // address of window name ); Parameters lpClassName Points to a null-terminated string that specifies the class name or is an atom that identifies the class-name string. If this parameter is an atom, it must be a global atom created by a previous call to the GlobalAddAtom function. The atom, a 16-bit value, must be placed in the low-order word of lpClassName; the high-order word must be zero. lpWindowName Points to a null-terminated string that specifies the window name (the window's title). If this parameter is NULL, all window names match. Return Value If the function succeeds, the return value is the handle of the window that has the specified class name and window name. If the function fails, the return value is NULL. To get extended error information, call GetLastError.
TUT: To call this function we need : LPCTSTR lpClassName = NIL // address of class name LPCTSTR lpWindowName = your choice // address of window name
The GetWindowThreadProcessId function retrieves the identifier of the thread that created the specified window and, optionally, the identifier of the process that created the window. This function supersedes the GetWindowTask function. DWORD GetWindowThreadProcessId( HWND hWnd, // handle of window LPDWORD lpdwProcessId // address of variable for process identifier ); Parameters hWnd Identifies the window. lpdwProcessId Points to a 32-bit value that receives the process identifier. If this parameter is not NULL, GetWindowThreadProcessId copies the identifier of the process to the 32-bit value; otherwise, it does not. Return Value The return value is the identifier of the thread that created the window.
TUT: To call this function we need : HWND hWnd = result from FindWindowA // handle of window LPDWORD lpdwProcessId = your choice // address of variable for process identifier We are now able to write a function which will relieve the access to a Process for us. I wrote this function in Delphi3. If someone asks for the assembler or c version, then I will write one for you too, but at this time iam to lazy ;) Anyway, it should not be that hard to figure it out yourself ! Here thus the Delphi version of the mentioned function:
(This function will in most cases find its use in a trainer i think)
METHOD2: ---------------- In this chapter we are going to write a Process Patcher. A Process Patcher will do the following tasks : - Getting commandline - Create new process and handle commandline to it - Wait until the process was fully initialized - Patch the process - Finally terminate and leave the new process alone A Process Patcher will be usefull if ... 1. the exe was compressed (i.e. Shrinker) 2. the exe was encrypted (i.e. PE-Crypt) 3. the app performs a CRC-Check on the exe 4. the exe was modified in any other way With a Process Patcher you dont have to care about the exe anymore, because it will patch the Process like in the first method of this tut. The difference is that we dont have to specify a window title, because we will use KERNEL32!CreateProcess and therefore we will automatically get the Process handle (with PROCESS_ALL_ACCESS) returned in a structure. Let us go through each task of the patcher : Getting commandline : ----------------------------- This may also be usefull if you have renamed the patcher.exe to app.exe . This way the app will receive the commandline from the patcher and thus the patcher will be fully transparency to the child process. Remark : do not change the name if the app performs a CRC-Check on the exe !!!, otherwise it will do the check on the patcher and thats even logical ;) Create new process and handle commandline to it : ------------------------------------------------------------------ Win95 does it the same way and again we will be fully transparency to the child process. Wait until the process was fully initialized : ------------------------------------------------------- This is necessary, because the memory of the child processes wasnt commited yet which means that there is garbage at this point. I used WaitForInputIdle to make sure the memory was commited. This function waits until the given process is waiting for user input. Remark : If this is too late for your app you may do compare constantly !!! Patch the process : ------------------------- After the process memory was commited and the byte check was ok we now can simply patch the process. Finally terminate and leave the new process alone : ------------------------------------------------------------------- This is optional , but dont forget to close the process and thread handles. Ok , before i give you the source here are the Descriptions of the functions from win32.hlp:
The CreateProcess function creates a new process and its primary thread. The new process executes the specified executable file. BOOL CreateProcess( LPCTSTR lpApplicationName, // pointer to name of executable module LPTSTR lpCommandLine, // pointer to command line string LPSECURITY_ATTRIBUTES lpProcessAttributes, // pointer to process security attributes LPSECURITY_ATTRIBUTES lpThreadAttributes, // pointer to thread security attributes BOOL bInheritHandles, // handle inheritance flag DWORD dwCreationFlags, // creation flags LPVOID lpEnvironment, // pointer to new environment block LPCTSTR lpCurrentDirectory, // pointer to current directory name LPSTARTUPINFO lpStartupInfo, // pointer to STARTUPINFO LPPROCESS_INFORMATION lpProcessInformation // pointer to PROCESS_INFORMATION ); Parameters lpApplicationName Pointer to a null-terminated string that specifies the module to execute. The string can specify the full path and filename of the module to execute. The string can specify a partial name. In that case, the function uses the current drive and current directory to complete the specification. The lpApplicationName parameter can be NULL. In that case, the module name must be the first white space-delimited token in the lpCommandLine string. The specified module can be a Win32-based application. It can be some other type of module (for example, MS-DOS or OS/2) if the appropriate subsystem is available on the local computer. Windows NT : If the executable module is a 16-bit application, lpApplicationName should be NULL, and the string pointed to by lpCommandLine should specify the executable module. A 16-bit application is one that executes as a VDM or WOW process. lpCommandLine Pointer to a null-terminated string that specifies the command line to execute. The lpCommandLine parameter can be NULL. In that case, the function uses the string pointed to by lpApplicationName as the command line. If both lpApplicationName and lpCommandLine are non-NULL, *lpApplicationName specifies the module to execute, and *lpCommandLine specifies the command line. The new process can use GetCommandLine to retrieve the entire command line. C runtime processes can use the argc and argv arguments. If lpApplicationName is NULL, the first white space-delimited token of the command line specifies the module name. If the filename does not contain an extension, .EXE is assumed. If the filename ends in a period (.) with no extension, or the filename contains a path, .EXE is not appended. If the filename does not contain a directory path, Windows searches for the executable file in the following sequence: 1. The directory from which the application loaded. 2. The current directory for the parent process. 3. Windows 95: The Windows system directory. Use the GetSystemDirectory function to get the path of this directory. Windows NT: The 32-bit Windows system directory. Use the GetSystemDirectory function to get the path of this directory. The name of this directory is SYSTEM32. 4. Windows NT only: The 16-bit Windows system directory. There is no Win32 function that obtains the path of this directory, but it is searched. The name of this directory is SYSTEM. 5. The Windows directory. Use the GetWindowsDirectory function to get the path of this directory. 6. The directories that are listed in the PATH environment variable. If the process to be created is an MS-DOS - based or Windows-based application, lpCommandLine should be a full command line in which the first element is the application name. Because this also works well for Win32-based applications, it is the most robust way to set lpCommandLine. lpProcessAttributes Points to a SECURITY_ATTRIBUTES structure that specifies the security attributes for the created process. If lpProcessAttributes is NULL, the process is created with a default security descriptor, and the resulting handle is not inherited. lpThreadAttributes Points to a SECURITY_ATTRIBUTES structure that specifies the security attributes for the primary thread of the new process. If lpThreadAttributes is NULL, the process is created with a default security descriptor, and the resulting handle is not inherited. bInheritHandles Indicates whether the new process inherits handles from the calling process. If TRUE, each inheritable open handle in the calling process is inherited by the new process. Inherited handles have the same value and access privileges as the original handles. dwCreationFlags Specifies additional flags that control the priority class and the creation of the process. The following creation flags can be specified in any combination, except as noted: Value Meaning CREATE_DEFAULT_ERROR_MODE The new process does not inherit the error mode of the calling process. Instead, CreateProcess gives the new process the current default error mode. An application sets the current default error mode by calling SetErrorMode.This flag is particularly useful for multi-threaded shell applications that run with hard errors disabled. The default behavior for CreateProcess is for the new process to inherit the error mode of the caller. Setting this flag changes that default behavior. CREATE_NEW_CONSOLE The new process has a new console, instead of inheriting the parent's console. This flag cannot be used with the DETACHED_PROCESS flag. CREATE_NEW_PROCESS_GROUP The new process is the root process of a new process group. The process group includes all processes that are descendants of this root process. The process ID of the new process group is the same as the process ID, which is returned in the lpProcessInformation parameter. Process groups are used by the GenerateConsoleCtrlEvent function to enable sending a CTRL+C or CTRL+BREAK signal to a group of console processes. CREATE_SEPARATE_WOW_VDM This flag is only valid only launching a 16-bit Windows program. If set, the new process is run in a private Virtual DOS Machine (VDM). By default, all 16-bit Windows programs are run in a single, shared VDM. The advantage of running separately is that a crash only kills the single VDM; any other programs running in distinct VDMs continue to function normally. Also, 16-bit Windows applications which are run in separate VDMs have separate input queues. That means that if one application hangs momentarily, applications in separate VDMs continue to receive input. CREATE_SHARED_WOW_VDM Windows NT: The flag is valid only when launching a 16-bit Windows program. If the DefaultSeparateVDM switch in the Windows section of WIN.INI is TRUE, this flag causes the CreateProcess function to override the switch and run the new process in the shared Virtual DOS Machine. CREATE_SUSPENDED The primary thread of the new process is created in a suspended state, and does not run until the ResumeThread function is called. CREATE_UNICODE_ENVIRONMENT If set, the environment block pointed to by lpEnvironment uses Unicode characters. If clear, the environment block uses ANSI characters. DEBUG_PROCESS If this flag is set, the calling process is treated as a debugger, and the new process is a process being debugged. The system notifies the debugger of all debug events that occur in the process being debugged. If you create a process with this flag set, only the calling thread (the thread that called CreateProcess) can call the WaitForDebugEvent function. DEBUG_ONLY_THIS_PROCESS if not set and the calling process is being debugged, the new process becomes another process being debugged by the calling process's debugger. If the calling process is not a process being debugged, no debugging-related actions occur. DETACHED_PROCESS For console processes, the new process does not have access to the console of the parent process. The new process can call the AllocConsole function at a later time to create a new console. This flag cannot be used with the CREATE_NEW_CONSOLE flag. The dwCreationFlags parameter also controls the new process's priority class, which is used in determining the scheduling priorities of the process's threads. If none of the following priority class flags is specified, the priority class defaults to NORMAL_PRIORITY_CLASS unless the priority class of the creating process is IDLE_PRIORITY_CLASS. In this case the default priority class of the child process is IDLE_PRIORITY_CLASS. One of the following flags can be specified: Priority Meaning HIGH_PRIORITY_CLASS Indicates a process that performs time-critical tasks that must be executed immediately for it to run correctly. The threads of a high-priority class process preempt the threads of normal-priority or idle-priority class processes. An example is Windows Task List, which must respond quickly when called by the user, regardless of the load on the operating system. Use extreme care when using the high-priority class, because a high-priority class CPU-bound application can use nearly all available cycles. IDLE_PRIORITY_CLASS Indicates a process whose threads run only when the system is idle and are preempted by the threads of any process running in a higher priority class. An example is a screen saver. The idle priority class is inherited by child processes. NORMAL_PRIORITY_CLASS Indicates a normal process with no special scheduling needs. REALTIME_PRIORITY_CLASS Indicates a process that has the highest possible priority. The threads of a real-time priority class process preempt the threads of all other processes, including operating system processes performing important tasks. For example, a real-time process that executes for more than a very brief interval can cause disk caches not to flush or cause the mouse to be unresponsive. lpEnvironment Points to an environment block for the new process. If this parameter is NULL, the new process uses the environment of the calling process. An environment block consists of a null-terminated block of null-terminated strings. Each string is in the form: name=value Because the equal sign is used as a separator, it must not be used in the name of an environment variable. If an application provides an environment block, rather than passing NULL for this parameter, the current directory information of the system drives is not automatically propagated to the new process. For a discussion of this situation and how to handle it, see the following Remarks section. An environment block can contain Unicode or ANSI characters. If the environment block pointed to by lpEnvironment contains Unicode characters, the dwCreationFlags field's CREATE_UNICODE_ENVIRONMENT flag will be set. If the block contains ANSI characters, that flag will be clear. Note that an ANSI environment block is terminated by two zero bytes: one for the last string, one more to terminate the block. A Unicode environment block is terminated by four zero bytes: two for the last string, two more to terminate the block. lpCurrentDirectory Points to a null-terminated string that specifies the current drive and directory for the child process. The string must be a full path and filename that includes a drive letter. If this parameter is NULL, the new process is created with the same current drive and directory as the calling process. This option is provided primarily for shells that need to start an application and specify its initial drive and working directory. lpStartupInfo Points to a STARTUPINFO structure that specifies how the main window for the new process should appear. lpProcessInformation Points to a PROCESS_INFORMATION structure that receives identification information about the new process. Return Value If the function succeeds, the return value is TRUE. If the function fails, the return value is FALSE. To get extended error information, call GetLastError.
TUT: wow ! this function has lotta paramaters ;) , but dont worry most of em can be NULL. lpApplicationName = your choice // pointer to name of executable module lpCommandLine = result of getcommandine // pointer to command line string lpProcessAttributes = NULL // pointer to process security attributes lpThreadAttributes = NULL // pointer to thread security attributes bInheritHandles = FALSE // handle inheritance flag dwCreationFlags = NORMAL_PRIORITY_CLASS // creation flags lpEnvironment = NULL // pointer to new environment block lpCurrentDirectory = NULL // pointer to current directory name lpStartupInfo = ? // pointer to STARTUPINFO lpProcessInformation = ? // pointer to PROCESS_INFORMATION Now we have a look at the STARTUPINFO structure : typedef struct _STARTUPINFO { // si DWORD cb; LPTSTR lpReserved; LPTSTR lpDesktop; LPTSTR lpTitle; DWORD dwX; DWORD dwY; DWORD dwXSize; DWORD dwYSize; DWORD dwXCountChars; DWORD dwYCountChars; DWORD dwFillAttribute; DWORD dwFlags; WORD wShowWindow; WORD cbReserved2; LPBYTE lpReserved2; HANDLE hStdInput; HANDLE hStdOutput; HANDLE hStdError; } STARTUPINFO, *LPSTARTUPINFO Its eneugh to initialize all values to zero and cb to sizeof(si). Now we have a look at the PROCESS_INFORMATION structure : typedef struct _PROCESS_INFORMATION { // pi HANDLE hProcess; HANDLE hThread; DWORD dwProcessId; DWORD dwThreadId; } PROCESS_INFORMATION; The PROCESS_INFORMATION structure is filled in by the CreateProcess function with information about a newly created process and its primary thread. Members hProcess Returns a handle to the newly created process. The handle is used to specify the process in all functions that perform operations on the process object. hThread Returns a handle to the primary thread of the newly created process. The handle is used to specify the thread in all functions that perform operations on the thread object. dwProcessId Returns a global process identifier that can be used to identify a process. The value is valid from the time the process is created until the time the process is terminated. dwThreadId Returns a global thread identifiers that can be used to identify a thread. The value is valid from the time the thread is created until the time the thread is terminated. TUT: This structure will be returned by CreateProcess and it includes the process handle. Now we got all parameters to create the process, but after it was created we have to wait until it was initialized. Therefore we must call WaitForInputIdle (hProcess, INFINITE) to make sure the whole virtual memory of the new process was commited, before we can patch it. Before we terminate we also have to close the process and thread handle. SOURCE: I wrote a simple Process-Patcher PPATCH.EXE which will patch COUNTERS.EXE. COUNTERS.EXE was shrinked and it consists only of a counter and a button. If you press the button it will decrement the counter by one and a MessageBox with "GO ON !!!" will pop up. If you have reach 0 the MessageBox will show you "GAME OVER !!!". Put both exe into the same dir and execute PPATCH.EXE. Sorry that counters.exe is over 100kb, but Shrinker does not accept small files ;) Here is the source of PPATCH
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