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1. #CRACK PROGRAM USING OLLYDBG 2 0 HOW TO#
2. #CRACK PROGRAM USING OLLYDBG 2 0 SOFTWARE#
3. #CRACK PROGRAM USING OLLYDBG 2 0 CODE#
4. #CRACK PROGRAM USING OLLYDBG 2 0 WINDOWS#

PIMAGE_SECTION_HEADER FindRDataSection(PBYTE pImageBase) Return (PIMAGE_NT_HEADERS)(pImageBase + pImageDosHeader->e_lfanew) PIMAGE_DOS_HEADER pImageDosHeader = (PIMAGE_DOS_HEADER)pImageBase PIMAGE_NT_HEADERS GetImageNtHeaders(PBYTE pImageBase)

#CRACK PROGRAM USING OLLYDBG 2 0 CODE#

The code example below checks the GlobalFlagsClear field in the memory of the running process and on the disk thus illustrating one of the popular anti debugging techniques: If an executable was initially created without the mentioned structure or with GlobalFlagsClear = 0, while on the disk or in the memory, the field will have a non-zero value indicating that there's a hidden debugger working. This structure has the GlobalFlagsClear field, which indicates which flags of the NtGlobalFlag field of the PEB structure should be reset. This structure is not built into an executable by default, but it can be added using a patch. The executable can include the IMAGE_LOAD_CONFIG_DIRECTORY structure, which contains additional configuration parameters for the system loader. NtGlobalFlag and IMAGE_LOAD_CONFIG_DIRECTORY To bypass the NtGlobalFlag check, just performing reverse the actions that we took before the check in other words, set the the NtGlobalFlag field of the PEB structure of the debugged process to 0 before this value is checked by the anti debugging protection. If (NtGlobalFlagWow64 & NT_GLOBAL_FLAG_DEBUGGED) Std::cout << "Stop debugging program!" << std::endl ĭWORD NtGlobalFlagWow64 = *(PDWORD)((PBYTE)pPeb64 + 0xBC) If (NtGlobalFlag & NT_GLOBAL_FLAG_DEBUGGED) #define NT_GLOBAL_FLAG_DEBUGGED (FLG_HEAP_ENABLE_TAIL_CHECK | FLG_HEAP_ENABLE_FREE_CHECK | FLG_HEAP_VALIDATE_PARAMETERS)ĭWORD NtGlobalFlag = *(PDWORD)((PBYTE)pPeb + offsetNtGlobalFlag) #define FLG_HEAP_VALIDATE_PARAMETERS 0x40 During debugging, such flags are set in the NtGlobalFlag field: The PEB structure also includes the NtGlobalFlag field, and its bit structure does not correspond to the NtGlobalFlag global system variable. The variable flags are undocumented, but the SDK includes the gflags utility, which allows you to edit a global flag value. This variable value is used for system tracing, debugging, and control. At boot, the NtGlobalFlag global system variable is initialized with the value from the system registry key:

#CRACK PROGRAM USING OLLYDBG 2 0 WINDOWS#

In Windows NT, there's a set of flags that are stored in the global variable NtGlobalFlag, which is common for the whole system. _declspec(allocate(".CRT$XLY"))PIMAGE_TLS_CALLBACK g_tlsCallback = TlsCallback TerminateProcess(GetCurrentProcess(), 0xBABEFACE) MessageBoxA(NULL, "Stop debugging program!", "Error", MB_OK | MB_ICONERROR) Var = 0xB15BADB0 // Required for TLS Callback call VOID NTAnopPI TlsCallback(PVOID DllHandle, DWORD Reason, VOID Reserved) The code below shows an example of elementary protection: This function detects if the calling process is being debugged by a user-mode debugger. Perhaps the simplest anti-debugging method is calling the IsDebuggerPresent function.

#CRACK PROGRAM USING OLLYDBG 2 0 SOFTWARE#

We won’t consider different theories of software protection, only practical examples.

#CRACK PROGRAM USING OLLYDBG 2 0 HOW TO#

This article presents popular anti-debugging techniques, starting from the simplest, and notes how to bypass them. The best way to be prepared for an attack is to know where one could come from. The main goal of various anti-reverse engineering techniques is simply to complicate the process as much as possible. We should mention right at the beginning that it's impossible to completely protect software from being reverse engineered. This article considers popular anti-cracking and anti-reverse engineering protection techniques, namely anti-debugging methods in Windows.