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How can the CE memory scanner be so fast?

 
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DanyDollaro
Expert Cheater
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Joined: 01 Aug 2019
Posts: 178
Location: Italy

PostPosted: Thu Nov 07, 2019 5:10 pm    Post subject: How can the CE memory scanner be so fast? Reply with quote

Recently I have created a function in C++ (a Memory Scanner) that receives as input:
the value to look for,
the first address from which to start the search,
the last address of the search,
the alignment with which to search;
and saves the addresses on which it found the desired value in a (dynamic) vector.
The function is this [C++] (UINT64 = 64bit unsigned integer):
Code:
std::vector<UINT64> ScannValue(HANDLE hProcess, UINT64 Value, UINT64 StartAddress, UINT64 LastAddress, BYTE Alignment)
{   
   std::vector<UINT64> Addresses;
   UINT64 Buffer = 0;

   while (StartAddress <= LastAddress)
   {
      ReadProcessMemory(hProcess, (LPVOID)StartAddress, &Buffer, Alignment, NULL);

      if (Value == Buffer)
      {
         Addresses.push_back(StartAddress);
      }

      StartAddress += Alignment;
   }

   return Addresses;
}

(The fact that I showed you the function`s code is irrelevant, the most important part are the results)

I tried to do a speed test of my function against the CE memory scanner (Spoiler: had won CE Laughing) I setted my function to look up from the address 0x0 to 0xFFFFFFFF, and set CE so that it scans from the address 0x0 to 0xFFFFFFFF (I changed the CE scan settings and ran the test several times) But CE has a speed stunning, he did all the scans in less than 1 second reporting +1300 results as opposed of my function which took 13 minutes and about 20 seconds to find 742 results (And the scan was not over yet).

After that, I want to ask you:
1) How many threads does CE use for a scan of this type ("New Scan" - 4 byte value)?
2) Scan all the bytes it finds in the range?
3) Skip the page scan if it is not inaccessible or unallocated?
4) Are there any other operations CE do to speed up the scan?
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Dark Byte
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Joined: 09 May 2003
Posts: 22133
Location: The netherlands

PostPosted: Thu Nov 07, 2019 5:29 pm    Post subject: This post has 1 review(s) Reply with quote

1: The total number of CPU cores in your system (/2 if hyperthreading is detected)

4:
Limit the number of ReadProcessMemory calls
CE first builds a list of all available memory regions. Then combines that into a list of ReadProcessMemory calls (up to a max block size specified in settings)
Then for each entry call ReadProcessMemory, scan the buffer for the value, and on to the next block

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DanyDollaro
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Reputation: 2

Joined: 01 Aug 2019
Posts: 178
Location: Italy

PostPosted: Thu Nov 07, 2019 7:44 pm    Post subject: Reply with quote

Thank you very much Dark Byte is an honor to have your answer Very Happy, I tried to replicate your algorithm and it has an impressive speed Shocked !!
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