Print Page - Peeping Tom: A Powerful PEEK/POKE library written using WinAPI

In regular QBasic, we had PEEK and POKE. In QB64, those functions are kept mostly for legacy and will overflow on modern variables. On the Wiki, there was code written in 2011 by Michael Calkins to give PEEK and POKE functionality back to QB64 without such issues (here:https://www.qb64.org/wiki/PEEK_and_POKE_Library (https://www.qb64.org/wiki/PEEK_and_POKE_Library)). It works ok but not great. It crashes quite often when trying to POKE the memory of a different process. So, in my endeavor to make trainers in QB64, I decided it was high-time someone made a good alternative to PEEK and POKE that allows you to change the memory of a different process/application. So, we have Peeping Tom. A library made using WinAPI's OpenProcess, ReadProcessMemory, and WriteProcessMemory functions. With this you can peekbyte, peekint, peeklong, peekint64, peekstring, pokebyte, pokeint, pokelong, pokeint64, and pokestring for ANY process that has read/writeable memory in the locations you are attempting to access.

A screenshot showing the library editing values in the exe compiled from the source:

And the source code (tested in 32 and 64 bit):

Code: QB64: [Select]

OPTION _EXPLICIT
 
$IF 64BIT THEN
    TYPE PROCESSENTRY32
        dwSize AS LONG
        cntUsage AS LONG
        th32ProcessID AS _INTEGER64
        th32DefaultHeapID AS _UNSIGNED _INTEGER64
        th32ModuleID AS LONG
        cntThreads AS LONG
        th32ParentProcessID AS LONG
        pcPriClassBase AS LONG
        dwFlags AS LONG
        szExeFile AS STRING * 260
    END TYPE
$ELSE
    TYPE PROCESSENTRY32
    dwSize AS LONG
    cntUsage AS LONG
    th32ProcessID AS LONG
    th32DefaultHeapID AS _UNSIGNED LONG
    th32ModuleID AS LONG
    cntThreads AS LONG
    th32ParentProcessID AS LONG
    pcPriClassBase AS LONG
    dwFlags AS LONG
    szExeFile AS STRING * 260
    END TYPE
$END IF
 
CONST PROCESS_VM_READ = &H0010
CONST PROCESS_QUERY_INFORMATION = &H0400
CONST PROCESS_VM_WRITE = &H0020
CONST PROCESS_VM_OPERATION = &H0008
CONST STANDARD_RIGHTS_REQUIRED = &H000F0000
CONST SYNCHRONIZE = &H00100000
CONST PROCESS_ALL_ACCESS = STANDARD_RIGHTS_REQUIRED OR SYNCHRONIZE OR &HFFFF
 
CONST TH32CS_INHERIT = &H80000000
CONST TH32CS_SNAPHEAPLIST = &H00000001
CONST TH32CS_SNAPMODULE = &H00000008
CONST TH32CS_SNAPMODULE32 = &H00000010
CONST TH32CS_SNAPPROCESS = &H00000002
CONST TH32CS_SNAPTHREAD = &H00000004
CONST TH32CS_SNAPALL = TH32CS_SNAPHEAPLIST OR TH32CS_SNAPMODULE OR TH32CS_SNAPPROCESS OR TH32CS_SNAPTHREAD
 
CONST TRUE = -1
CONST FALSE = 0
 
DECLARE DYNAMIC LIBRARY "Kernel32"
    FUNCTION CreateToolhelp32Snapshot& (BYVAL dwFlags AS LONG, BYVAL th32ProcessID AS LONG)
    FUNCTION Process32First%% (BYVAL hSnapshot AS LONG, BYVAL lppe AS _OFFSET)
    FUNCTION Process32Next%% (BYVAL hSnapshot AS LONG, BYVAL lppe AS _OFFSET)
    FUNCTION OpenProcess& (BYVAL dwDesiredAccess AS LONG, BYVAL bInheritHandle AS _BYTE, BYVAL dwProcessId AS LONG)
    FUNCTION ReadProcessMemory%% (BYVAL hProcess AS LONG, BYVAL lpBaseAddress AS _OFFSET, BYVAL lpBuffer AS _OFFSET, BYVAL nSize AS LONG, BYVAL lpNumberOfBytesRead AS _OFFSET)
    FUNCTION WriteProcessMemory%% (BYVAL hProcess AS LONG, BYVAL lpBaseAddress AS _OFFSET, BYVAL lpBuffer AS _OFFSET, BYVAL nSize AS LONG, BYVAL lpNumberOfBytesWritten AS _OFFSET)
    FUNCTION CloseHandle%% (BYVAL hObject AS LONG)
END DECLARE
 
DECLARE CUSTOMTYPE LIBRARY
    FUNCTION strlen& (BYVAL ptr AS _UNSIGNED _OFFSET)
END DECLARE
 
_TITLE "Peeping Tom: A Powerful PEEK/POKE"
 
DIM test AS STRING
test = "This is a test" + CHR$(0)
DIM exe AS STRING
exe = MID$(COMMAND$(0), _INSTRREV(COMMAND$(0), "\") + 1)
PRINT CHR$(peekbyte(exe, _OFFSET(test)))
PRINT peekstring(exe, _OFFSET(test))
 
DIM testint AS INTEGER
testint = 320
PRINT peekint(exe, _OFFSET(testint))
 
DIM testlong AS LONG
testlong = &HFF
PRINT peeklong(exe, _OFFSET(testlong))
 
DIM testint64 AS _INTEGER64
testint64 = 922337
PRINT peekint64(exe, _OFFSET(testint64))
 
DIM a AS _BYTE
a = pokebyte(exe, _OFFSET(test), ASC("S"))
PRINT peekstring(exe, _OFFSET(test))
 
a = pokeint(exe, _OFFSET(testint), 312)
PRINT peekint(exe, _OFFSET(testint))
 
a = pokelong(exe, _OFFSET(testlong), &HFE)
PRINT peeklong(exe, _OFFSET(testlong))
 
a = pokeint64(exe, _OFFSET(testint64), 922345)
PRINT peekint64(exe, _OFFSET(testint64))
 
a = pokestring(exe, _OFFSET(test), "This is NOT a test" + CHR$(0))
PRINT peekstring(exe, _OFFSET(test))
 
FUNCTION peekbyte%% (process AS STRING, address AS _UNSIGNED _OFFSET)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                DIM result AS _BYTE
                memo = ReadProcessMemory(hProcess, address, _OFFSET(result), 1, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    peekbyte = result
END FUNCTION
 
FUNCTION peekint% (process AS STRING, address AS _UNSIGNED _OFFSET)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                DIM result AS INTEGER
                memo = ReadProcessMemory(hProcess, address, _OFFSET(result), 2, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    peekint = result
END FUNCTION
 
FUNCTION peeklong& (process AS STRING, address AS _UNSIGNED _OFFSET)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                DIM result AS LONG
                memo = ReadProcessMemory(hProcess, address, _OFFSET(result), 4, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    peeklong = result
END FUNCTION
 
FUNCTION peekint64&& (process AS STRING, address AS _UNSIGNED _OFFSET)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                DIM result AS _INTEGER64
                memo = ReadProcessMemory(hProcess, address, _OFFSET(result), 8, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    peekint64 = result
END FUNCTION
 
FUNCTION peekstring$ (process AS STRING, address AS _UNSIGNED _OFFSET)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                DIM result AS STRING
                result = SPACE$(PointerLen(address))
                memo = ReadProcessMemory(hProcess, address, _OFFSET(result), LEN(result), 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    peekstring = result
END FUNCTION
 
FUNCTION pokebyte%% (process AS STRING, address AS _UNSIGNED _OFFSET, value AS _BYTE)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                memo = WriteProcessMemory(hProcess, address, _OFFSET(value), 1, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    pokebyte = memo
END FUNCTION
 
FUNCTION pokeint%% (process AS STRING, address AS _UNSIGNED _OFFSET, value AS INTEGER)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                memo = WriteProcessMemory(hProcess, address, _OFFSET(value), 2, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    pokeint = memo
END FUNCTION
 
FUNCTION pokelong%% (process AS STRING, address AS _UNSIGNED _OFFSET, value AS LONG)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                memo = WriteProcessMemory(hProcess, address, _OFFSET(value), 4, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    pokelong = memo
END FUNCTION
 
FUNCTION pokeint64%% (process AS STRING, address AS _UNSIGNED _OFFSET, value AS _INTEGER64)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                memo = WriteProcessMemory(hProcess, address, _OFFSET(value), 8, 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    pokeint64 = memo
END FUNCTION
 
FUNCTION pokestring%% (process AS STRING, address AS _UNSIGNED _OFFSET, value AS STRING)
    DIM hProcessSnap AS LONG
    DIM hProcess AS LONG
    DIM pe32 AS PROCESSENTRY32
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
    pe32.dwSize = LEN(pe32)
    IF Process32First(hProcessSnap, _OFFSET(pe32)) THEN
        WHILE Process32Next(hProcessSnap, _OFFSET(pe32))
            IF _STRCMP(LEFT$(pe32.szExeFile, INSTR(pe32.szExeFile, ".exe" + CHR$(0)) + 3), process) = 0 THEN
                hProcess = OpenProcess(PROCESS_VM_READ OR PROCESS_QUERY_INFORMATION OR PROCESS_VM_WRITE OR PROCESS_VM_OPERATION, FALSE, pe32.th32ProcessID)
                DIM memo AS _BYTE
                memo = WriteProcessMemory(hProcess, address, _OFFSET(value), LEN(value), 0)
                EXIT WHILE
            END IF
        WEND
    END IF
    DIM closeh AS LONG
    closeh = CloseHandle(hProcessSnap)
    closeh = CloseHandle(hProcess)
    pokestring = memo
END FUNCTION
 
FUNCTION PointerLen& (value AS _OFFSET)
    PointerLen = strlen(value)
END FUNCTION

Feel free to change it up as you see fit. Note: You will have to know where the address of the data you want to change is located. I do have a function that searches out strings and can be modified to search for numbers (and is not included here) BUT you DO NOT want to try it that way as you will MOST CERTAINLY WRITE TO THE WRONG ADDRESS since there are multiple places where a value could be the same as the one you are searching for. After I make my tutorial on creating game trainers you will see that you should use Cheat Engine https://www.cheatengine.org/ (https://www.cheatengine.org/) to locate the BASE addresses you are wanting to change. Base addresses remain constant between launches of a program with several offsets in place to arrive at the variable address that does change between launches. Be VERY CAREFUL modifying memory in programs. Don't go all will-nilly changing things for the heck of it. Take care in what you do.

Cool. I'll be giving this a try. I've played around with mcaulkins code quite a bit and did have some crashing issues now and then. Thanks for sharing.

- Dav

Quote from: Dav on October 16, 2020, 05:55:38 pm

Cool. I'll be giving this a try. I've played around with mcaulkins code quite a bit and did have some crashing issues now and then. Thanks for sharing.

- Dav

Yeah, his code is pretty good for some things but I had times where just using his library at all in my code made it not even get to the point of loading the screen of the program. I've had plenty of good luck with this code so far.

The next step would be to offer free cloud services to banks.

Quote from: Richard Frost on October 16, 2020, 11:17:01 pm

The next step would be to offer free cloud services to banks.

@Richard Frost Eh?

If a bank runs a process on your computer, you can monkey with it,
vary the amount of bananas in accounts.

Quote from: Richard Frost on October 16, 2020, 11:23:56 pm

If a bank runs a process on your computer, you can monkey with it,
vary the amount of bananas in accounts.

@Richard Frost I don't know why they would do that but sure, I guess.....

Updated 10/17/2020

Fixed the peekstring function so it doesn't just call peekbyte but instead grabs the entire string in one go.

Updated each function by placing an EXIT WHILE so on the off-chance that there is another process running of the same name that it doesn't change that as well.

QB64.org Forum

Active Forums => Programs => Topic started by: SpriggsySpriggs on October 16, 2020, 04:36:39 pm