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shellcode_base.c
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196 lines (184 loc) · 5.74 KB
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#include "shellcode_base.h"
//===============================================================================================//
typedef struct _UNICODE_STR {
USHORT Length;
USHORT MaximumLength;
PWSTR pBuffer;
} UNICODE_STR, *PUNICODE_STR;
// WinDbg> dt -v ntdll!_LDR_DATA_TABLE_ENTRY
//__declspec( align(8) )
typedef struct _LDR_DATA_TABLE_ENTRY {
// LIST_ENTRY InLoadOrderLinks; // As we search from PPEB_LDR_DATA->InMemoryOrderModuleList we dont use the first
// entry.
LIST_ENTRY InMemoryOrderModuleList;
LIST_ENTRY InInitializationOrderModuleList;
PVOID DllBase;
PVOID EntryPoint;
ULONG SizeOfImage;
UNICODE_STR FullDllName;
UNICODE_STR BaseDllName;
ULONG Flags;
SHORT LoadCount;
SHORT TlsIndex;
LIST_ENTRY HashTableEntry;
ULONG TimeDateStamp;
} LDR_DATA_TABLE_ENTRY, *PLDR_DATA_TABLE_ENTRY;
// WinDbg> dt -v ntdll!_PEB_LDR_DATA
typedef struct _PEB_LDR_DATA //, 7 elements, 0x28 bytes
{
DWORD dwLength;
DWORD dwInitialized;
LPVOID lpSsHandle;
LIST_ENTRY InLoadOrderModuleList;
LIST_ENTRY InMemoryOrderModuleList;
LIST_ENTRY InInitializationOrderModuleList;
LPVOID lpEntryInProgress;
} PEB_LDR_DATA, *PPEB_LDR_DATA;
// WinDbg> dt -v ntdll!_PEB_FREE_BLOCK
typedef struct _PEB_FREE_BLOCK // 2 elements, 0x8 bytes
{
struct _PEB_FREE_BLOCK *pNext;
DWORD dwSize;
} PEB_FREE_BLOCK, *PPEB_FREE_BLOCK;
// struct _PEB is defined in Winternl.h but it is incomplete
// WinDbg> dt -v ntdll!_PEB
typedef struct __PEB // 65 elements, 0x210 bytes
{
BYTE bInheritedAddressSpace;
BYTE bReadImageFileExecOptions;
BYTE bBeingDebugged;
BYTE bSpareBool;
LPVOID lpMutant;
LPVOID lpImageBaseAddress;
PPEB_LDR_DATA pLdr;
LPVOID lpProcessParameters;
LPVOID lpSubSystemData;
LPVOID lpProcessHeap;
PRTL_CRITICAL_SECTION pFastPebLock;
LPVOID lpFastPebLockRoutine;
LPVOID lpFastPebUnlockRoutine;
DWORD dwEnvironmentUpdateCount;
LPVOID lpKernelCallbackTable;
DWORD dwSystemReserved;
DWORD dwAtlThunkSListPtr32;
PPEB_FREE_BLOCK pFreeList;
DWORD dwTlsExpansionCounter;
LPVOID lpTlsBitmap;
DWORD dwTlsBitmapBits[2];
LPVOID lpReadOnlySharedMemoryBase;
LPVOID lpReadOnlySharedMemoryHeap;
LPVOID lpReadOnlyStaticServerData;
LPVOID lpAnsiCodePageData;
LPVOID lpOemCodePageData;
LPVOID lpUnicodeCaseTableData;
DWORD dwNumberOfProcessors;
DWORD dwNtGlobalFlag;
LARGE_INTEGER liCriticalSectionTimeout;
DWORD dwHeapSegmentReserve;
DWORD dwHeapSegmentCommit;
DWORD dwHeapDeCommitTotalFreeThreshold;
DWORD dwHeapDeCommitFreeBlockThreshold;
DWORD dwNumberOfHeaps;
DWORD dwMaximumNumberOfHeaps;
LPVOID lpProcessHeaps;
LPVOID lpGdiSharedHandleTable;
LPVOID lpProcessStarterHelper;
DWORD dwGdiDCAttributeList;
LPVOID lpLoaderLock;
DWORD dwOSMajorVersion;
DWORD dwOSMinorVersion;
WORD wOSBuildNumber;
WORD wOSCSDVersion;
DWORD dwOSPlatformId;
DWORD dwImageSubsystem;
DWORD dwImageSubsystemMajorVersion;
DWORD dwImageSubsystemMinorVersion;
DWORD dwImageProcessAffinityMask;
DWORD dwGdiHandleBuffer[34];
LPVOID lpPostProcessInitRoutine;
LPVOID lpTlsExpansionBitmap;
DWORD dwTlsExpansionBitmapBits[32];
DWORD dwSessionId;
ULARGE_INTEGER liAppCompatFlags;
ULARGE_INTEGER liAppCompatFlagsUser;
LPVOID lppShimData;
LPVOID lpAppCompatInfo;
UNICODE_STR usCSDVersion;
LPVOID lpActivationContextData;
LPVOID lpProcessAssemblyStorageMap;
LPVOID lpSystemDefaultActivationContextData;
LPVOID lpSystemAssemblyStorageMap;
DWORD dwMinimumStackCommit;
} _PEB, *_PPEB;
typedef struct {
WORD offset : 12;
WORD type : 4;
} IMAGE_RELOC, *PIMAGE_RELOC;
#define cast(t, a) ((t)(a))
#define cast_offset(t, p, o) ((t)((uint8_t *)(p) + (o)))
uint32_t get_delta() {
uint32_t r = 0;
#ifndef _WIN64
__asm {
call delta;
delta:
pop eax;
sub eax, offset delta;
mov r, eax
}
#endif
return r;
}
uint32_t calc_hashW2(wchar_t *str, int len) {
uint32_t seed = 131; // 31 131 1313 13131 131313 etc..
uint32_t hash = 0;
for (int i = 0; i < len; i++) {
wchar_t s = *str++;
if (s >= 'a') s = s - 0x20;
hash = hash * seed + s;
}
return (hash & 0x7FFFFFFF);
}
HMODULE get_kernel32_base() {
_PPEB peb = 0;
#ifdef _WIN64
peb = (_PPEB)__readgsqword(0x60); // peb
#else
peb = (_PPEB)__readfsdword(0x30);
#endif
LIST_ENTRY *entry = peb->pLdr->InMemoryOrderModuleList.Flink;
while (entry) {
PLDR_DATA_TABLE_ENTRY e = (PLDR_DATA_TABLE_ENTRY)entry;
if (calc_hashW2(e->BaseDllName.pBuffer, e->BaseDllName.Length / 2) == Kernel32Lib_Hash) {
return (HMODULE)e->DllBase;
}
entry = entry->Flink;
}
return 0;
};
// BKDRHash
uint32_t calc_hash(char *str) {
uint32_t seed = 131; // 31 131 1313 13131 131313 etc..
uint32_t hash = 0;
while (*str) {
hash = hash * seed + (*str++);
}
return (hash & 0x7FFFFFFF);
}
void *get_proc_address_from_hash(HMODULE module, uint32_t func_hash, _GetProcAddress get_proc_address) {
PIMAGE_DOS_HEADER dosh = cast(PIMAGE_DOS_HEADER, module);
PIMAGE_NT_HEADERS nth = cast_offset(PIMAGE_NT_HEADERS, module, dosh->e_lfanew);
PIMAGE_DATA_DIRECTORY dataDict = &nth->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
if (dataDict->VirtualAddress == 0 || dataDict->Size == 0) return 0;
PIMAGE_EXPORT_DIRECTORY exportDict = cast_offset(PIMAGE_EXPORT_DIRECTORY, module, dataDict->VirtualAddress);
if(exportDict->NumberOfNames == 0) return 0;
uint32_t *fn = cast_offset(uint32_t *, module, exportDict->AddressOfNames);
uint32_t *fa = cast_offset(uint32_t *, module, exportDict->AddressOfFunctions);
uint16_t *ord = cast_offset(uint16_t *, module, exportDict->AddressOfNameOrdinals);
for (uint32_t i = 0; i < exportDict->NumberOfNames; i++) {
char *name = cast_offset(char *, module, fn[i]);
if (calc_hash(name) != func_hash) continue;
return get_proc_address == 0 ? cast_offset(void*, module, fa[ord[i]]) : get_proc_address(module, name);
}
return 0;
}