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Help with reading a string from memory and the memory

 
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chinawhite
How do I cheat?
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Joined: 10 Sep 2019
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PostPosted: Tue Sep 10, 2019 12:26 am    Post subject: Help with reading a string from memory and the memory Reply with quote

Hey guys,
Could you help me out a bit please? I'm kinda new to this memory stuff and I'm a bit stuck... here's what I'm trying to do and what goes wrong:
The ultimate goal is to read and then write a static string in a process that changes the address of the string on each execution, but for the sake of learning, I'll focus here on just reading the string correctly from memory and I'll handle the writing later. So...
From what I've understand so far I should find the base address in this case, so that's what (I think) I did. I did a pointer scan, got millions of results, relaunched the process, re-scanned till I got down to only 4 results which had the same base address and I presume that's the base address. And now here comes my troubles.
This is the result in CE:
Base Address: 101A6040; Offsets from 0 - 6: 34 4C 54 74 18 C50 88.
And I have this code:
Code:

    var
      GamePID: Cardinal;
      dat: array[1..47] of Char;
      read: SIZE_T;
      Str: String;
    begin
      GamePID := 1337;
      GamePID := OpenProcess(PROCESS_ALL_ACCESS, false, GamePID);
      Win32Check(GamePID <> 0);
      if not ReadProcessMemory(GamePID, Pointer($101A6040), @dat, 47, read) then RaiseLastOSError;
      Str := String(dat);
      ShowMessage(Str);
    end;

Now here comes my troubles:
1. From what I understand, I'd also have to add the offsets somehow to the code, not only the base address - how to do that?
(PS: the string is 47 characters long so I presume that's how I should declare "dat" array?)
2. The code isn't working, meaning Win32Check returns "Code 5 - Access denied" for this process. I have enabled SeDebugPrivilege for my application and also ran it as admin. How is CE able to access this process, does it do it via a driver or something?
3. From what I understand on this, I should use also VirtualProtectEx, but I don't know how to add that to the code either.
So help with any or both of the questions/points would really really be appreciated. Thanks.
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t328163
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Joined: 19 Dec 2017
Posts: 25

PostPosted: Mon Sep 16, 2019 8:12 am    Post subject: Reply with quote

You could just write a software driver in plain C that scans the entire physical memory address space for the string.
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atom0s
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PostPosted: Mon Sep 16, 2019 2:41 pm    Post subject: Reply with quote

1. You need to read the memory of each step in the offset list. Each offset points to a pointer, so you need to read that value then use it in the next step of the reading. There are examples of this all over the forum in various languages, the jist is the same since the API call is the same in all languages.

2. Opening a process handle can be rejected if the process is protected. But, also if the running application does not have permission to use the desired flag. Using PROCESS_ALL_ACCESS requires admin privileges and is generally discouraged from being used anyway in game-hacking related situations. Specify the flags you need properly rather than using the 'all access' flag.

If you still want to use all access, then you need to both make sure your app is running as admin and that you have the proper access (as you mentioned via SeDebugPrivilege).

If you are running the program through the IDE for debugging purposes, the IDE must be started in admin mode as well.

3. VirtualProtectEx should only be needed if you need to adjust the memorys protection. Unless the application has page guards on the pointers, then you shouldn't need to adjust the protection to read the pointers or the value. But, if the memory is protected from writing you may need to adjust it while writing back a string to the end pointer.

You can read more on how VirtualProtectEx works here:
https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualprotectex

Parameter wise:
- hProcess - Should be the handle returned from OpenProcess.
- lpAddress - Should be the final address where the string is located you want to write to.
- dwSize - The size of data you plan to write. (The system will automatically round up to the proper size of the memory page as needed. Keep in mind this can change protection levels of multiple pages depending on what you give this.)
- flNewProtect - The new protection you wish to set on the memory page. (Generally, you'll want PAGE_EXECUTE_READWRITE for most things.)
- lpflOldProtect - A variable to hold the original protection before you modified it.

Depending on if the process is protected with an anti-cheat or similar, you will need to make sure to restore the page protection that was previously set otherwise it may trigger a detection due to the protection adjustment made.

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