149 lines
4.2 KiB
C++
149 lines
4.2 KiB
C++
/*******************************************************************
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I recently re-read a paper from Adam Chester titled:
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"Protecting Your Malware with blockdlls and ACG"
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link: https://blog.xpnsec.com/protecting-your-malware/
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It was neat, I was curious how the APIs in this code
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worked, so I decided to reverse them. The tl;dr is
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that the functions used to block non-MS sign DLLs
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is very-very easy to implement without using or
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importing the functions:
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InitializeProcThreadAttributeList
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UpdateProcThreadAttribute
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I was able to recreate these functions in just
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a few lines of C code and some IDA F5s.
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Thanks to DTM, Jonas Lyk, and coldzer0 to helping me
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trim the fat off these APIs. Under the hood these
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functions do lots of unnecessary things (for our purpose)
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and they helped speed up the process.
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Anyway, nothing revolutionary, but its neat. :)
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-smelly
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*********************************************************************/
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#include <Windows.h>
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typedef struct _PROC_THREAD_ATTRIBUTE {
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ULONG64 Attribute;
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ULONG64 Size;
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ULONG64 Value;
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}PROC_THREAD_ATTRIBUTE, *PPROC_THREAD_ATTRIBUTE;
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typedef struct _PROC_THREAD_ATTRIBUTE_LIST {
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ULONG PresentFlags;
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ULONG AttributeCount;
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ULONG LastAttribute;
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ULONG SpareUlong0;
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struct _PROC_THREAD_ATTRIBUTE* ExtendedFlagsAttribute;
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struct _PROC_THREAD_ATTRIBUTE Attributes[1];
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}PROC_THREAD_ATTRIBUTE_LIST, * PPROC_THREAD_ATTRIBUTE_LIST;
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BOOL RtlInitializeProcThreadAttributeList(LPPROC_THREAD_ATTRIBUTE_LIST lpAttributeList, DWORD dwAttributeCount, DWORD dwFlags, PSIZE_T lpSize)
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{
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BOOL bFlag = FALSE;
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DWORD dwSize = ERROR_SUCCESS;
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if (dwFlags || (dwAttributeCount > 0x1B))
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{
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SetLastError(ERROR_INVALID_PARAMETER);
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return bFlag;
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}
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dwSize = (24 * (dwAttributeCount + 1));
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if (lpAttributeList && *lpSize >= dwSize)
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{
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lpAttributeList->PresentFlags = 0;
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lpAttributeList->ExtendedFlagsAttribute = 0;
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lpAttributeList->AttributeCount = dwAttributeCount;
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lpAttributeList->LastAttribute = 0;
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bFlag = TRUE;
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}
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else
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SetLastError(ERROR_INSUFFICIENT_BUFFER);
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*lpSize = dwSize;
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return bFlag;
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}
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SIZE_T RtlGetProcThreadAttributeListSize(VOID)
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{
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SIZE_T dwSize = 0;
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RtlInitializeProcThreadAttributeList(NULL, 1, 0, &dwSize);
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return dwSize;
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}
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VOID RtlUpdateProcThreadAttribute(LPPROC_THREAD_ATTRIBUTE_LIST AttributeList, DWORD_PTR Attribute, PVOID Policy, SIZE_T Size)
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{
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PPROC_THREAD_ATTRIBUTE ExtendedAttributes;
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AttributeList->PresentFlags |= (1 << (Attribute & 0x0000FFFF));
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ExtendedAttributes = AttributeList->Attributes;
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ExtendedAttributes->Attribute = Attribute;
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ExtendedAttributes->Size = Size;
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ExtendedAttributes->Value = (ULONG64)Policy;
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AttributeList->LastAttribute++;
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return;
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}
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INT main(VOID)
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{
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DWORD dwError = ERROR_SUCCESS;
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BOOL bFlag = FALSE;
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PROCESS_INFORMATION Pi; ZeroMemory(&Pi, sizeof(PROCESS_INFORMATION));
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STARTUPINFOEXW Si; ZeroMemory(&Si, sizeof(STARTUPINFOEXW));
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Si.StartupInfo.cb = sizeof(STARTUPINFOEXW);
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PPROC_THREAD_ATTRIBUTE_LIST ThreadAttributes = NULL;
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SIZE_T dwAttributeSize = 0;
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DWORD64 Policy = PROCESS_CREATION_MITIGATION_POLICY_BLOCK_NON_MICROSOFT_BINARIES_ALWAYS_ON;
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dwAttributeSize = RtlGetProcThreadAttributeListSize();
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if (dwAttributeSize == 0)
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goto EXIT_ROUTINE;
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ThreadAttributes = (PPROC_THREAD_ATTRIBUTE_LIST)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, dwAttributeSize);
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if (ThreadAttributes == NULL)
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goto EXIT_ROUTINE;
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if (!RtlInitializeProcThreadAttributeList(ThreadAttributes, 1, 0, &dwAttributeSize))
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goto EXIT_ROUTINE;
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RtlUpdateProcThreadAttribute(ThreadAttributes, PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY, &Policy, sizeof(DWORD64));
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Si.lpAttributeList = ThreadAttributes;
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if (!CreateProcessW((PWCHAR)L"C:\\Windows\\System32\\calc.exe", NULL, NULL, NULL, TRUE, EXTENDED_STARTUPINFO_PRESENT, NULL, NULL, &Si.StartupInfo, &Pi))
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goto EXIT_ROUTINE;
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WaitForSingleObject(Pi.hProcess, INFINITE);
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bFlag = TRUE;
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EXIT_ROUTINE:
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if (!bFlag)
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dwError = GetLastError();
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if (ThreadAttributes)
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HeapFree(GetProcessHeap(), HEAP_ZERO_MEMORY, (PPROC_THREAD_ATTRIBUTE_LIST)ThreadAttributes);
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if(Pi.hProcess)
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CloseHandle(Pi.hProcess);
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if(Pi.hThread)
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CloseHandle(Pi.hThread);
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return dwError;
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} |