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Random Access Violations

 
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iPromise
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Joined: 27 Jun 2009
Posts: 529
Location: Canada
PostPosted: Thu May 06, 2010 5:25 pm    Post subject: Random Access Violations Reply with quote
Hello CEF community,

As you guys well know I coded a memory scanner to simply find addresses that I can use for my hacks. However, whenever I do a next scan with my memory scanner it tends to give me a random access violation (mostly on games not other non-gaming applications). So I saw that maybe I needed to protect the memory to PAGE_READWRITE or any other memory readable constants. So I tested it and gave it a run and it kept giving me random access violations.

So heres my code for my next scan:

Code:

void NextScan(HWND hWndDlg)
{
   int Min = 0; int Max = SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_GETCOUNT, 0, 0);

   char TypeBuf[500] = {0};

   GetWindowTextA(GetDlgItem(hWndDlg, IDC_COMBO1), (LPSTR) TypeBuf, 500);

   char ValueBuf[500] = {0};

   GetWindowTextA(GetDlgItem(hWndDlg, IDC_EDIT1), (LPSTR) ValueBuf, 500);

   string ValueStr;

   ValueStr += (LPSTR) ValueBuf;

   stringstream ConvertValue; unsigned int Value;

   ConvertValue << (LPSTR) ValueBuf; ConvertValue >> Value;   

   char Scan[500] = {0};

   GetWindowTextA(GetDlgItem(hWndDlg, IDC_COMBO2), (LPSTR) Scan, 500);

   DWORD lpflOldProtect;

   if (!strcmp(Scan, "Exact Value"))
   {
      for (int i = Min; i <= Max; i ++)
      {
         char AddressBuf[500] = {0};

         SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_GETTEXT, (WPARAM) i, (LPARAM) (LPTSTR) AddressBuf);

         stringstream ConvertAddress(AddressBuf); LPVOID lpAddress;

         ConvertAddress >> lpAddress;

         DWORD dwAddress = (DWORD) lpAddress;         

         VirtualProtect((LPVOID) dwAddress, 4, PAGE_READWRITE, &lpflOldProtect);         
         
         if (((!strcmp(TypeBuf, "Byte")) && *(BYTE*) dwAddress != (BYTE) Value) ||
            ((!strcmp(TypeBuf, "2 Bytes")) && *(WORD*) dwAddress != (WORD) Value) ||
            ((!strcmp(TypeBuf, "4 Bytes")) && *(DWORD*) dwAddress != (DWORD) Value) ||
            ((!strcmp(TypeBuf, "8 Bytes")) && *(UINT64*) dwAddress != (UINT64) Value))
         {
            SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_DELETESTRING, (WPARAM) i, 0);
         }      

         VirtualProtect((LPVOID) dwAddress, 4, lpflOldProtect, &lpflOldProtect);   
      }

      GetResults(hWndDlg);
   }

   if (!strcmp(Scan, "Decreased.."))
   {
      for (int i = Min; i <= Max; i ++)
      {
         char AddressBuf[500] = {0};

         SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_GETTEXT, (WPARAM) i, (LPARAM) (LPTSTR) AddressBuf);

         stringstream ConvertAddress(AddressBuf); LPVOID lpAddress;

         ConvertAddress >> lpAddress;

         DWORD dwAddress = (DWORD) lpAddress;   

         VirtualProtect((LPVOID) dwAddress, 4, PAGE_READWRITE, &lpflOldProtect);      

         if (((!strcmp(TypeBuf, "Byte")) && ((*(BYTE*) dwAddress) >= ((BYTE) Value))) ||
            ((!strcmp(TypeBuf, "2 Bytes")) && ((*(WORD*) dwAddress) >= ((WORD) Value))) ||
            ((!strcmp(TypeBuf, "4 Bytes")) && ((*(DWORD*) dwAddress) >= ((DWORD) Value))) ||
            ((!strcmp(TypeBuf, "8 Bytes")) && ((*(UINT64*) dwAddress) >= ((UINT64) Value))))
         {
            SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_DELETESTRING, (WPARAM) i, 0);
         }         

         VirtualProtect((LPVOID) dwAddress, 4, lpflOldProtect, &lpflOldProtect);   
      }

      GetResults(hWndDlg);
   }

   if (!strcmp(Scan, "Increased.."))
   {
      for (int i = Min; i <= Max; i ++)
      {
         char AddressBuf[500] = {0};

         SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_GETTEXT, (WPARAM) i, (LPARAM) (LPTSTR) AddressBuf);

         stringstream ConvertAddress(AddressBuf); LPVOID lpAddress;

         ConvertAddress >> lpAddress;

         DWORD dwAddress = (DWORD) lpAddress;         

         VirtualProtect((LPVOID) dwAddress, 4, PAGE_READWRITE, &lpflOldProtect);      

         if (((!strcmp(TypeBuf, "Byte")) && *(BYTE*) dwAddress <= (BYTE) Value) ||
            ((!strcmp(TypeBuf, "2 Bytes")) && *(WORD*) dwAddress <= (WORD) Value) ||
            ((!strcmp(TypeBuf, "4 Bytes")) && *(DWORD*) dwAddress <= (DWORD) Value) ||
            ((!strcmp(TypeBuf, "8 Bytes")) && *(UINT64*) dwAddress <= (UINT64) Value))
         {
            SendMessage(GetDlgItem(hWndDlg, IDC_LIST1), LB_DELETESTRING, (WPARAM) i, 0);
         }         

         VirtualProtect((LPVOID) dwAddress, 4, lpflOldProtect, &lpflOldProtect);   
      }

      GetResults(hWndDlg);
   }
}


Please, suggestions and comments can help me out.
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Slugsnack
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PostPosted: Thu May 06, 2010 5:48 pm    Post subject: Reply with quote
most likely the memory that you are trying to read is dynamic and got freed between now and your last scan.
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iPromise
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PostPosted: Thu May 06, 2010 5:56 pm    Post subject: Reply with quote
Hmm, so should I use VirtualQuery() on the address to check if its still readable memory?
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Slugsnack
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PostPosted: Thu May 06, 2010 6:01 pm    Post subject: Reply with quote
could do but it's probably not worth it unless you do it in a way such that doesn't involve calling it for every single address in your list. i would just wrap the reading part for that in a try/except. if it throws an exception, just remove that address and assume it's been de-allocated
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Flyte
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PostPosted: Thu May 06, 2010 7:15 pm    Post subject: This post has 1 review(s) Reply with quote
I feel sorry for you, so:

memory.hpp

Your missions, should you choose to accept them:
  1. Write a CachedRemoteMemory class that extends RemoteMemory for faster scans.
  2. Add a cache for the value that was found on the last scan, enabling scans such as 'incremented'.
  3. Understand what is going on... shouldn't be hard for one who has mastered C++ (lol). No comments, since comments are ezmode.

(As noted in the file, largely untested so something is probably broken somewhere... I suppose that's what you get for a 1 hour hack job.)

Here is how to use (part of) it.

Code:
#include <iostream>
#include <list>
#include "memory.hpp"

void ExampleOne(int i) {
   std::list<Address> items;
   Scanner scanner;

   std::cout << "Starting..." << std::endl;
   if(scanner.Scan<int>(i, items)) {
      do {
         std::cout << "Scanning..." << std::endl;
      } while(scanner.ScanNext(++i, items) > 1);
      if(items.size() == 1) {
         std::cout << "Done." << std::endl;

         std::cout << "i = " << i << std::endl
            << "&i = " << &i << std::endl;

         Address addr = items.front();

         std::cout << "addr = " << (int)addr << std::endl
            << "&addr = " << (void *)addr.Value() << std::endl;

         std::cout << "Setting addr = " << i + 42 << std::endl;
         addr = i + 42;
         std::cout << "i = " << i << std::endl;
      } else {
         std::cout << "Something broke. Go fix it." << std::endl;
      }
   }
}

bool GreaterThan(int a, int b) {
   return a > b;
}

bool LessThan(int a, int b) {
   return a < b;
}

void ExampleTwo(int i) {
   std::list<Address> items;
   Scanner scanner;

   std::cout << "Starting..." << std::endl;
   if(scanner.Scan(i-10, items, GreaterThan)) {
      std::cout << items.size() << " items greater than " << i-10 << "." << std::endl;
      if(scanner.ScanNext(i+10, items, LessThan)) {
         std::cout << items.size() << " items also less than " << i+10 << "." << std::endl;
         if(scanner.ScanNext(i-2, items, GreaterThan)) {
            std::cout << items.size() << " items also greater than " << i-2 << "." << std::endl;
            if(scanner.ScanNext(i+2, items, LessThan)) {
               std::cout << items.size() << " items also less than " << i+2 << "." << std::endl;
            }
         }
      }
   }
}

void PrintTestHeader(int i) {
   std::cout << std::endl << "Test " << i << std::endl << "--------------" << std::endl;
}

int main()
{
   // Fast
   PrintTestHeader(1);
   ExampleOne(3);

   // Slow - Will probably crash (bad_alloc) on a big process. You need to store results in a file for such a situation.
   PrintTestHeader(2);
   ExampleOne(0);

   // Same as above.
   PrintTestHeader(3);
   ExampleTwo(100);

   return 0;
}


Edit: Doesn't currently compile, I went and fucked a function up. brb while I fix it.
Edit 2: I believe I've fixed it. C++ and SEH together shit all over everything.

Last edited by Flyte on Thu May 06, 2010 11:45 pm; edited 1 time in total
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iPromise
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PostPosted: Thu May 06, 2010 9:44 pm    Post subject: Reply with quote
Thanks a lot Smile
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Flyte
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PostPosted: Thu May 06, 2010 11:46 pm    Post subject: Reply with quote
Remind me not to hack something like this up again... every time I look at it I find another thing that makes me go "what the fuck was I thinking?".

iPromise wrote:
Thanks a lot Smile


No problem. The bill will be in the mail shortly.
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Slugsnack
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PostPosted: Fri May 07, 2010 11:28 am    Post subject: Reply with quote
Code:
#ifndef MEMORY_HPP // Header guards. One of the few legit uses of the C preprocessor (lol)
#define MEMORY_HPP


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blitz02
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PostPosted: Fri May 07, 2010 11:47 am    Post subject: Reply with quote
Oh. I still can't do it.
I don't know anymore.

Help me again, this is my scenario.

if( I Scan to 0x08000000 - upward)
I am allowed.. no error and I can change values..

But if I scan 0x07FFFFFF and below.. I'm gettin crashed..
No posted errors.. It just exits my program..

I think my head will explode..
I tried different types of memory scanner code,
also added virtual query..Still it crashes.. What am I suppose to do Crying or Very sad
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hcavolsdsadgadsg
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PostPosted: Fri May 07, 2010 2:33 pm    Post subject: Reply with quote
blitz02 wrote:
Still it crashes.. What am I suppose to do Crying or Very sad


use the debugger instead of playing guessing games
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blitz02
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PostPosted: Sat May 08, 2010 6:40 am    Post subject: Reply with quote
slovach wrote:
blitz02 wrote:
Still it crashes.. What am I suppose to do Crying or Very sad


use the debugger instead of playing guessing games


Finally I did it! thanks!
I can already scan areas and make them to be displayed.

But another problem occurs.
I cannot write at them, even though they are PAGE_READWRITE.
gonna do another debugging.. cya lates! Razz
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