OffenSive Csharp Development Part4
本文是OffenSive Csharp Development 系列的第四篇文章，主要讲解如何使用D/Invoke来进行Syscall调用。
首先我们要理解系统调用的概念。在Windows中，进程的体系结构分为两种处理器访问模式——用户模式(user mode)和内核模式(kernel mode)。这两种模式是为了保护用户应用程序免于访问和修改任何重要的系统数据。用户应用程序（例如Chrome，Word等）均在用户模式下运行，而系统代码（例如系统服务和设备驱动程序）均在内核模式下运行。如图：
在内核模式下，处理器允许程序访问所有系统内存以及所有CPU指令。有一些x86和x64的处理器也使用ring levels这样的术语来区分这两种模式。
使用ring level特权模式的处理器定义了四个特权级别（rings）来保护系统代码和数据。下图是一个ring levels的示例。
Windows只使用其中的两个级别：Ring0表示内核模式，Ring3表示用户模式。在处理器正常运行期间，处理器会根据其上运行的代码类型在这两种模式之间进行切换。为了让用户应用程序能够在内核模式下访问这些数据结构，进程使用了一个特殊的处理器指令触发器，叫做“ syscall”。该指令触发了处理器访问模式的转换，并允许处理器访问内核中的系统服务调用代码。我们使用windbg来查看该过程。
x ntdll!NtFlushInstructionCache
u 00007ffb`f7f3e330
此时我们便看到了整个过程以及其对应的汇编代码：
mov r10,rcx
mov eax,0E3h
syscall
ret那么0E3h就是函数NtFlushInstructionCache的系统调用号，其完整列表可以参考：https://j00ru.vexillium.org/syscalls/nt/64/ 而D / Invoke有一个出色的方法GetSyscallStub，该方法可以在ntdll中找到给定API的syscall方法。
以NtFlushInstructionCache为例，我们需要先来定义它的委托。
[UnmanagedFunctionPointer(CallingConvention.StdCall)]
delegate NTSTATUS NtFlushInstructionCache(
Process processHandle,
IntPtr address,
int bytes
);结构体NTSTATUS可以在https://www.pinvoke.net/default.aspx/Enums/NtStatus.html找到：
[Flags]
enum NTSTATUS : uint
{
// Success
Success = 0x00000000,
Wait0 = 0x00000000,
Wait1 = 0x00000001,
Wait2 = 0x00000002,
Wait3 = 0x00000003,
Wait63 = 0x0000003f,
Abandoned = 0x00000080,
AbandonedWait0 = 0x00000080,
AbandonedWait1 = 0x00000081,
AbandonedWait2 = 0x00000082,
AbandonedWait3 = 0x00000083,
AbandonedWait63 = 0x000000bf,
UserApc = 0x000000c0,
KernelApc = 0x00000100,
Alerted = 0x00000101,
Timeout = 0x00000102,
Pending = 0x00000103,
Reparse = 0x00000104,
MoreEntries = 0x00000105,
NotAllAssigned = 0x00000106,
SomeNotMapped = 0x00000107,
OpLockBreakInProgress = 0x00000108,
VolumeMounted = 0x00000109,
RxActCommitted = 0x0000010a,
NotifyCleanup = 0x0000010b,
NotifyEnumDir = 0x0000010c,
NoQuotasForAccount = 0x0000010d,
PrimaryTransportConnectFailed = 0x0000010e,
PageFaultTransition = 0x00000110,
PageFaultDemandZero = 0x00000111,
PageFaultCopyOnWrite = 0x00000112,
PageFaultGuardPage = 0x00000113,
PageFaultPagingFile = 0x00000114,
CrashDump = 0x00000116,
ReparseObject = 0x00000118,
NothingToTerminate = 0x00000122,
ProcessNotInJob = 0x00000123,
ProcessInJob = 0x00000124,
ProcessCloned = 0x00000129,
FileLockedWithOnlyReaders = 0x0000012a,
FileLockedWithWriters = 0x0000012b,
// Informational
Informational = 0x40000000,
ObjectNameExists = 0x40000000,
ThreadWasSuspended = 0x40000001,
WorkingSetLimitRange = 0x40000002,
ImageNotAtBase = 0x40000003,
RegistryRecovered = 0x40000009,
// Warning
Warning = 0x80000000,
GuardPageViolation = 0x80000001,
DatatypeMisalignment = 0x80000002,
Breakpoint = 0x80000003,
SingleStep = 0x80000004,
BufferOverflow = 0x80000005,
NoMoreFiles = 0x80000006,
HandlesClosed = 0x8000000a,
PartialCopy = 0x8000000d,
DeviceBusy = 0x80000011,
InvalidEaName = 0x80000013,
EaListInconsistent = 0x80000014,
NoMoreEntries = 0x8000001a,
LongJump = 0x80000026,
DllMightBeInsecure = 0x8000002b,
// Error
Error = 0xc0000000,
Unsuccessful = 0xc0000001,
NotImplemented = 0xc0000002,
InvalidInfoClass = 0xc0000003,
InfoLengthMismatch = 0xc0000004,
AccessViolation = 0xc0000005,
InPageError = 0xc0000006,
PagefileQuota = 0xc0000007,
InvalidHandle = 0xc0000008,
BadInitialStack = 0xc0000009,
BadInitialPc = 0xc000000a,
InvalidCid = 0xc000000b,
TimerNotCanceled = 0xc000000c,
InvalidParameter = 0xc000000d,
NoSuchDevice = 0xc000000e,
NoSuchFile = 0xc000000f,
InvalidDeviceRequest = 0xc0000010,
EndOfFile = 0xc0000011,
WrongVolume = 0xc0000012,
NoMediaInDevice = 0xc0000013,
NoMemory = 0xc0000017,
ConflictingAddresses = 0xc0000018,
NotMappedView = 0xc0000019,
UnableToFreeVm = 0xc000001a,
UnableToDeleteSection = 0xc000001b,
IllegalInstruction = 0xc000001d,
AlreadyCommitted = 0xc0000021,
AccessDenied = 0xc0000022,
BufferTooSmall = 0xc0000023,
ObjectTypeMismatch = 0xc0000024,
NonContinuableException = 0xc0000025,
BadStack = 0xc0000028,
NotLocked = 0xc000002a,
NotCommitted = 0xc000002d,
InvalidParameterMix = 0xc0000030,
ObjectNameInvalid = 0xc0000033,
ObjectNameNotFound = 0xc0000034,
ObjectNameCollision = 0xc0000035,
ObjectPathInvalid = 0xc0000039,
ObjectPathNotFound = 0xc000003a,
ObjectPathSyntaxBad = 0xc000003b,
DataOverrun = 0xc000003c,
DataLate = 0xc000003d,
DataError = 0xc000003e,
CrcError = 0xc000003f,
SectionTooBig = 0xc0000040,
PortConnectionRefused = 0xc0000041,
InvalidPortHandle = 0xc0000042,
SharingViolation = 0xc0000043,
QuotaExceeded = 0xc0000044,
InvalidPageProtection = 0xc0000045,
MutantNotOwned = 0xc0000046,
SemaphoreLimitExceeded = 0xc0000047,
PortAlreadySet = 0xc0000048,
SectionNotImage = 0xc0000049,
SuspendCountExceeded = 0xc000004a,
ThreadIsTerminating = 0xc000004b,
BadWorkingSetLimit = 0xc000004c,
IncompatibleFileMap = 0xc000004d,
SectionProtection = 0xc000004e,
EasNotSupported = 0xc000004f,
EaTooLarge = 0xc0000050,
NonExistentEaEntry = 0xc0000051,
NoEasOnFile = 0xc0000052,
EaCorruptError = 0xc0000053,
FileLockConflict = 0xc0000054,
LockNotGranted = 0xc0000055,
DeletePending = 0xc0000056,
CtlFileNotSupported = 0xc0000057,
UnknownRevision = 0xc0000058,
RevisionMismatch = 0xc0000059,
InvalidOwner = 0xc000005a,
InvalidPrimaryGroup = 0xc000005b,
NoImpersonationToken = 0xc000005c,
CantDisableMandatory = 0xc000005d,
NoLogonServers = 0xc000005e,
NoSuchLogonSession = 0xc000005f,
NoSuchPrivilege = 0xc0000060,
PrivilegeNotHeld = 0xc0000061,
InvalidAccountName = 0xc0000062,
UserExists = 0xc0000063,
NoSuchUser = 0xc0000064,
GroupExists = 0xc0000065,
NoSuchGroup = 0xc0000066,
MemberInGroup = 0xc0000067,
MemberNotInGroup = 0xc0000068,
LastAdmin = 0xc0000069,
WrongPassword = 0xc000006a,
IllFormedPassword = 0xc000006b,
PasswordRestriction = 0xc000006c,
LogonFailure = 0xc000006d,
AccountRestriction = 0xc000006e,
InvalidLogonHours = 0xc000006f,
InvalidWorkstation = 0xc0000070,
PasswordExpired = 0xc0000071,
AccountDisabled = 0xc0000072,
NoneMapped = 0xc0000073,
TooManyLuidsRequested = 0xc0000074,
LuidsExhausted = 0xc0000075,
InvalidSubAuthority = 0xc0000076,
InvalidAcl = 0xc0000077,
InvalidSid = 0xc0000078,
InvalidSecurityDescr = 0xc0000079,
ProcedureNotFound = 0xc000007a,
InvalidImageFormat = 0xc000007b,
NoToken = 0xc000007c,
BadInheritanceAcl = 0xc000007d,
RangeNotLocked = 0xc000007e,
DiskFull = 0xc000007f,
ServerDisabled = 0xc0000080,
ServerNotDisabled = 0xc0000081,
TooManyGuidsRequested = 0xc0000082,
GuidsExhausted = 0xc0000083,
InvalidIdAuthority = 0xc0000084,
AgentsExhausted = 0xc0000085,
InvalidVolumeLabel = 0xc0000086,
SectionNotExtended = 0xc0000087,
NotMappedData = 0xc0000088,
ResourceDataNotFound = 0xc0000089,
ResourceTypeNotFound = 0xc000008a,
ResourceNameNotFound = 0xc000008b,
ArrayBoundsExceeded = 0xc000008c,
FloatDenormalOperand = 0xc000008d,
FloatDivideByZero = 0xc000008e,
FloatInexactResult = 0xc000008f,
FloatInvalidOperation = 0xc0000090,
FloatOverflow = 0xc0000091,
FloatStackCheck = 0xc0000092,
FloatUnderflow = 0xc0000093,
IntegerDivideByZero = 0xc0000094,
IntegerOverflow = 0xc0000095,
PrivilegedInstruction = 0xc0000096,
TooManyPagingFiles = 0xc0000097,
FileInvalid = 0xc0000098,
InsufficientResources = 0xc000009a,
InstanceNotAvailable = 0xc00000ab,
PipeNotAvailable = 0xc00000ac,
InvalidPipeState = 0xc00000ad,
PipeBusy = 0xc00000ae,
IllegalFunction = 0xc00000af,
PipeDisconnected = 0xc00000b0,
PipeClosing = 0xc00000b1,
PipeConnected = 0xc00000b2,
PipeListening = 0xc00000b3,
InvalidReadMode = 0xc00000b4,
IoTimeout = 0xc00000b5,
FileForcedClosed = 0xc00000b6,
ProfilingNotStarted = 0xc00000b7,
ProfilingNotStopped = 0xc00000b8,
NotSameDevice = 0xc00000d4,
FileRenamed = 0xc00000d5,
CantWait = 0xc00000d8,
PipeEmpty = 0xc00000d9,
CantTerminateSelf = 0xc00000db,
InternalError = 0xc00000e5,
InvalidParameter1 = 0xc00000ef,
InvalidParameter2 = 0xc00000f0,
InvalidParameter3 = 0xc00000f1,
InvalidParameter4 = 0xc00000f2,
InvalidParameter5 = 0xc00000f3,
InvalidParameter6 = 0xc00000f4,
InvalidParameter7 = 0xc00000f5,
InvalidParameter8 = 0xc00000f6,
InvalidParameter9 = 0xc00000f7,
InvalidParameter10 = 0xc00000f8,
InvalidParameter11 = 0xc00000f9,
InvalidParameter12 = 0xc00000fa,
ProcessIsTerminating = 0xc000010a,
MappedFileSizeZero = 0xc000011e,
TooManyOpenedFiles = 0xc000011f,
Cancelled = 0xc0000120,
CannotDelete = 0xc0000121,
InvalidComputerName = 0xc0000122,
FileDeleted = 0xc0000123,
SpecialAccount = 0xc0000124,
SpecialGroup = 0xc0000125,
SpecialUser = 0xc0000126,
MembersPrimaryGroup = 0xc0000127,
FileClosed = 0xc0000128,
TooManyThreads = 0xc0000129,
ThreadNotInProcess = 0xc000012a,
TokenAlreadyInUse = 0xc000012b,
PagefileQuotaExceeded = 0xc000012c,
CommitmentLimit = 0xc000012d,
InvalidImageLeFormat = 0xc000012e,
InvalidImageNotMz = 0xc000012f,
InvalidImageProtect = 0xc0000130,
InvalidImageWin16 = 0xc0000131,
LogonServer = 0xc0000132,
DifferenceAtDc = 0xc0000133,
SynchronizationRequired = 0xc0000134,
DllNotFound = 0xc0000135,
IoPrivilegeFailed = 0xc0000137,
OrdinalNotFound = 0xc0000138,
EntryPointNotFound = 0xc0000139,
ControlCExit = 0xc000013a,
InvalidAddress = 0xc0000141,
PortNotSet = 0xc0000353,
DebuggerInactive = 0xc0000354,
CallbackBypass = 0xc0000503,
PortClosed = 0xc0000700,
MessageLost = 0xc0000701,
InvalidMessage = 0xc0000702,
RequestCanceled = 0xc0000703,
RecursiveDispatch = 0xc0000704,
LpcReceiveBufferExpected = 0xc0000705,
LpcInvalidConnectionUsage = 0xc0000706,
LpcRequestsNotAllowed = 0xc0000707,
ResourceInUse = 0xc0000708,
ProcessIsProtected = 0xc0000712,
VolumeDirty = 0xc0000806,
FileCheckedOut = 0xc0000901,
CheckOutRequired = 0xc0000902,
BadFileType = 0xc0000903,
FileTooLarge = 0xc0000904,
FormsAuthRequired = 0xc0000905,
VirusInfected = 0xc0000906,
VirusDeleted = 0xc0000907,
TransactionalConflict = 0xc0190001,
InvalidTransaction = 0xc0190002,
TransactionNotActive = 0xc0190003,
TmInitializationFailed = 0xc0190004,
RmNotActive = 0xc0190005,
RmMetadataCorrupt = 0xc0190006,
TransactionNotJoined = 0xc0190007,
DirectoryNotRm = 0xc0190008,
CouldNotResizeLog = 0xc0190009,
TransactionsUnsupportedRemote = 0xc019000a,
LogResizeInvalidSize = 0xc019000b,
RemoteFileVersionMismatch = 0xc019000c,
CrmProtocolAlreadyExists = 0xc019000f,
TransactionPropagationFailed = 0xc0190010,
CrmProtocolNotFound = 0xc0190011,
TransactionSuperiorExists = 0xc0190012,
TransactionRequestNotValid = 0xc0190013,
TransactionNotRequested = 0xc0190014,
TransactionAlreadyAborted = 0xc0190015,
TransactionAlreadyCommitted = 0xc0190016,
TransactionInvalidMarshallBuffer = 0xc0190017,
CurrentTransactionNotValid = 0xc0190018,
LogGrowthFailed = 0xc0190019,
ObjectNoLongerExists = 0xc0190021,
StreamMiniversionNotFound = 0xc0190022,
StreamMiniversionNotValid = 0xc0190023,
MiniversionInaccessibleFromSpecifiedTransaction = 0xc0190024,
CantOpenMiniversionWithModifyIntent = 0xc0190025,
CantCreateMoreStreamMiniversions = 0xc0190026,
HandleNoLongerValid = 0xc0190028,
NoTxfMetadata = 0xc0190029,
LogCorruptionDetected = 0xc0190030,
CantRecoverWithHandleOpen = 0xc0190031,
RmDisconnected = 0xc0190032,
EnlistmentNotSuperior = 0xc0190033,
RecoveryNotNeeded = 0xc0190034,
RmAlreadyStarted = 0xc0190035,
FileIdentityNotPersistent = 0xc0190036,
CantBreakTransactionalDependency = 0xc0190037,
CantCrossRmBoundary = 0xc0190038,
TxfDirNotEmpty = 0xc0190039,
IndoubtTransactionsExist = 0xc019003a,
TmVolatile = 0xc019003b,
RollbackTimerExpired = 0xc019003c,
TxfAttributeCorrupt = 0xc019003d,
EfsNotAllowedInTransaction = 0xc019003e,
TransactionalOpenNotAllowed = 0xc019003f,
TransactedMappingUnsupportedRemote = 0xc0190040,
TxfMetadataAlreadyPresent = 0xc0190041,
TransactionScopeCallbacksNotSet = 0xc0190042,
TransactionRequiredPromotion = 0xc0190043,
CannotExecuteFileInTransaction = 0xc0190044,
TransactionsNotFrozen = 0xc0190045,
MaximumNtStatus = 0xffffffff
}然后就是获取函数的问题了：
IntPtr stub = Generic.GetSyscallStub("NtFlushInstructionCache");
NtFlushInstructionCache NtFlushInstructionCaches = (NtFlushInstructionCache)Marshal.GetDelegateForFunctionPointer(stub, typeof(NtFlushInstructionCache));调用：
var processHandle = Process.GetProcessById(1796);
var status = NtFlushInstructionCaches(processHandle, IntPtr.Zero, 0);
Console.WriteLine(status);最后的效果：
那么我们也可以用它来上线我们的CobaltStrike。即：
OpenProcess / VirtualAllocEx / WriteProcessMemory / CreateRemoteThread
且可以看到一个未使用ntdll的线程，代码地址：https://github.com/lengjibo/OffenSiveCSharp/tree/master/SyscallCsharp
本文参与 腾讯云自媒体同步曝光计划，分享自微信公众号。
原始发表：2021-03-23，如有侵权请联系 cloudcommunity@tencent.com 删除
评论
登录后参与评论
推荐阅读
腾讯云开发者
